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io_uring: fix fget/fput handling
This isn't a straight port of commit84c4e1f89ffor aio.c, since io_uring doesn't use files in exactly the same way. But it's pretty close. See the commit message for that commit. This essentially fixes a use-after-free with the poll command handling, but it takes cue from Linus's approach to just simplifying the file handling. We move the setup of the file into a higher level location, so the individual commands don't have to deal with it. And then we release the reference when we free the associated io_kiocb. Fixes:221c5eb233("io_uring: add support for IORING_OP_POLL") Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
parent
d530a402a1
commit
09bb839434
230
fs/io_uring.c
230
fs/io_uring.c
@ -189,6 +189,10 @@ struct sqe_submit {
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bool needs_fixed_file;
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};
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/*
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* First field must be the file pointer in all the
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* iocb unions! See also 'struct kiocb' in <linux/fs.h>
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*/
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struct io_poll_iocb {
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struct file *file;
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struct wait_queue_head *head;
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@ -198,8 +202,15 @@ struct io_poll_iocb {
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struct wait_queue_entry wait;
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};
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/*
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* NOTE! Each of the iocb union members has the file pointer
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* as the first entry in their struct definition. So you can
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* access the file pointer through any of the sub-structs,
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* or directly as just 'ki_filp' in this struct.
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*/
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struct io_kiocb {
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union {
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struct file *file;
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struct kiocb rw;
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struct io_poll_iocb poll;
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};
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@ -431,6 +442,8 @@ static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
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static void io_free_req(struct io_kiocb *req)
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{
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if (req->file && !(req->flags & REQ_F_FIXED_FILE))
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fput(req->file);
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io_ring_drop_ctx_refs(req->ctx, 1);
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kmem_cache_free(req_cachep, req);
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}
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@ -448,45 +461,34 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
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struct list_head *done)
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{
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void *reqs[IO_IOPOLL_BATCH];
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int file_count, to_free;
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struct file *file = NULL;
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struct io_kiocb *req;
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int to_free;
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file_count = to_free = 0;
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to_free = 0;
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while (!list_empty(done)) {
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req = list_first_entry(done, struct io_kiocb, list);
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list_del(&req->list);
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io_cqring_fill_event(ctx, req->user_data, req->error, 0);
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if (refcount_dec_and_test(&req->refs))
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reqs[to_free++] = req;
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(*nr_events)++;
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/*
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* Batched puts of the same file, to avoid dirtying the
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* file usage count multiple times, if avoidable.
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*/
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if (!(req->flags & REQ_F_FIXED_FILE)) {
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if (!file) {
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file = req->rw.ki_filp;
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file_count = 1;
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} else if (file == req->rw.ki_filp) {
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file_count++;
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if (refcount_dec_and_test(&req->refs)) {
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/* If we're not using fixed files, we have to pair the
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* completion part with the file put. Use regular
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* completions for those, only batch free for fixed
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* file.
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*/
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if (req->flags & REQ_F_FIXED_FILE) {
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reqs[to_free++] = req;
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if (to_free == ARRAY_SIZE(reqs))
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io_free_req_many(ctx, reqs, &to_free);
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} else {
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fput_many(file, file_count);
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file = req->rw.ki_filp;
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file_count = 1;
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io_free_req(req);
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}
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}
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if (to_free == ARRAY_SIZE(reqs))
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io_free_req_many(ctx, reqs, &to_free);
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}
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io_commit_cqring(ctx);
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if (file)
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fput_many(file, file_count);
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io_commit_cqring(ctx);
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io_free_req_many(ctx, reqs, &to_free);
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}
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@ -609,19 +611,12 @@ static void kiocb_end_write(struct kiocb *kiocb)
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}
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}
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static void io_fput(struct io_kiocb *req)
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{
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if (!(req->flags & REQ_F_FIXED_FILE))
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fput(req->rw.ki_filp);
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}
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static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
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{
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struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
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kiocb_end_write(kiocb);
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io_fput(req);
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io_cqring_add_event(req->ctx, req->user_data, res, 0);
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io_put_req(req);
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}
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@ -738,31 +733,18 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
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const struct io_uring_sqe *sqe = s->sqe;
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struct io_ring_ctx *ctx = req->ctx;
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struct kiocb *kiocb = &req->rw;
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unsigned ioprio, flags;
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int fd, ret;
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unsigned ioprio;
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int ret;
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if (!req->file)
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return -EBADF;
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/* For -EAGAIN retry, everything is already prepped */
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if (req->flags & REQ_F_PREPPED)
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return 0;
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flags = READ_ONCE(sqe->flags);
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fd = READ_ONCE(sqe->fd);
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if (force_nonblock && !io_file_supports_async(req->file))
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force_nonblock = false;
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files ||
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(unsigned) fd >= ctx->nr_user_files))
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return -EBADF;
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kiocb->ki_filp = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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if (s->needs_fixed_file)
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return -EBADF;
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kiocb->ki_filp = io_file_get(state, fd);
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if (unlikely(!kiocb->ki_filp))
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return -EBADF;
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if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
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force_nonblock = false;
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}
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kiocb->ki_pos = READ_ONCE(sqe->off);
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kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
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kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
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@ -771,7 +753,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
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if (ioprio) {
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ret = ioprio_check_cap(ioprio);
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if (ret)
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goto out_fput;
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return ret;
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kiocb->ki_ioprio = ioprio;
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} else
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@ -779,39 +761,26 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
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ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
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if (unlikely(ret))
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goto out_fput;
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return ret;
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if (force_nonblock) {
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kiocb->ki_flags |= IOCB_NOWAIT;
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req->flags |= REQ_F_FORCE_NONBLOCK;
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}
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if (ctx->flags & IORING_SETUP_IOPOLL) {
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ret = -EOPNOTSUPP;
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if (!(kiocb->ki_flags & IOCB_DIRECT) ||
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!kiocb->ki_filp->f_op->iopoll)
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goto out_fput;
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return -EOPNOTSUPP;
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req->error = 0;
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kiocb->ki_flags |= IOCB_HIPRI;
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kiocb->ki_complete = io_complete_rw_iopoll;
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} else {
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if (kiocb->ki_flags & IOCB_HIPRI) {
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ret = -EINVAL;
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goto out_fput;
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}
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if (kiocb->ki_flags & IOCB_HIPRI)
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return -EINVAL;
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kiocb->ki_complete = io_complete_rw;
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}
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req->flags |= REQ_F_PREPPED;
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return 0;
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out_fput:
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if (!(flags & IOSQE_FIXED_FILE)) {
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/*
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* in case of error, we didn't use this file reference. drop it.
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*/
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if (state)
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state->used_refs--;
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io_file_put(state, kiocb->ki_filp);
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}
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return ret;
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}
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static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
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@ -968,16 +937,14 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
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return ret;
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file = kiocb->ki_filp;
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ret = -EBADF;
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if (unlikely(!(file->f_mode & FMODE_READ)))
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goto out_fput;
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ret = -EINVAL;
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return -EBADF;
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if (unlikely(!file->f_op->read_iter))
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goto out_fput;
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return -EINVAL;
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ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
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if (ret)
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goto out_fput;
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return ret;
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iov_count = iov_iter_count(&iter);
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ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
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@ -999,10 +966,6 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
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}
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}
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kfree(iovec);
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out_fput:
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/* Hold on to the file for -EAGAIN */
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if (unlikely(ret && ret != -EAGAIN))
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io_fput(req);
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return ret;
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}
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@ -1020,17 +983,15 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
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if (ret)
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return ret;
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ret = -EBADF;
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file = kiocb->ki_filp;
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if (unlikely(!(file->f_mode & FMODE_WRITE)))
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goto out_fput;
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ret = -EINVAL;
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return -EBADF;
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if (unlikely(!file->f_op->write_iter))
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goto out_fput;
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return -EINVAL;
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ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
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if (ret)
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goto out_fput;
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return ret;
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iov_count = iov_iter_count(&iter);
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@ -1062,10 +1023,6 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
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}
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out_free:
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kfree(iovec);
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out_fput:
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/* Hold on to the file for -EAGAIN */
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if (unlikely(ret && ret != -EAGAIN))
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io_fput(req);
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return ret;
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}
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@ -1080,16 +1037,6 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
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if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
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return -EINVAL;
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/*
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* Twilight zone - it's possible that someone issued an opcode that
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* has a file attached, then got -EAGAIN on submission, and changed
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* the sqe before we retried it from async context. Avoid dropping
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* a file reference for this malicious case, and flag the error.
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*/
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if (req->rw.ki_filp) {
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err = -EBADF;
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io_fput(req);
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}
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io_cqring_add_event(ctx, user_data, err, 0);
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io_put_req(req);
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return 0;
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@ -1098,9 +1045,9 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
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static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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{
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struct io_ring_ctx *ctx = req->ctx;
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unsigned flags;
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int fd;
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if (!req->file)
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return -EBADF;
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/* Prep already done (EAGAIN retry) */
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if (req->flags & REQ_F_PREPPED)
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return 0;
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@ -1110,20 +1057,6 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
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return -EINVAL;
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fd = READ_ONCE(sqe->fd);
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flags = READ_ONCE(sqe->flags);
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files || fd >= ctx->nr_user_files))
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return -EBADF;
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req->rw.ki_filp = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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req->rw.ki_filp = fget(fd);
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if (unlikely(!req->rw.ki_filp))
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return -EBADF;
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}
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req->flags |= REQ_F_PREPPED;
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return 0;
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}
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@ -1153,7 +1086,6 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
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end > 0 ? end : LLONG_MAX,
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fsync_flags & IORING_FSYNC_DATASYNC);
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io_fput(req);
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io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
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io_put_req(req);
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return 0;
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@ -1220,7 +1152,6 @@ static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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static void io_poll_complete(struct io_kiocb *req, __poll_t mask)
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{
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io_cqring_add_event(req->ctx, req->user_data, mangle_poll(mask), 0);
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io_fput(req);
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io_put_req(req);
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}
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@ -1314,34 +1245,20 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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struct io_poll_iocb *poll = &req->poll;
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struct io_ring_ctx *ctx = req->ctx;
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struct io_poll_table ipt;
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unsigned flags;
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__poll_t mask;
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u16 events;
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int fd;
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if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
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return -EINVAL;
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if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
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return -EINVAL;
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if (!poll->file)
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return -EBADF;
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INIT_WORK(&req->work, io_poll_complete_work);
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events = READ_ONCE(sqe->poll_events);
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poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
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flags = READ_ONCE(sqe->flags);
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fd = READ_ONCE(sqe->fd);
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files || fd >= ctx->nr_user_files))
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return -EBADF;
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poll->file = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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poll->file = fget(fd);
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}
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if (unlikely(!poll->file))
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return -EBADF;
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poll->head = NULL;
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poll->woken = false;
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poll->canceled = false;
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@ -1380,8 +1297,6 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
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out:
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if (unlikely(ipt.error)) {
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if (!(flags & IOSQE_FIXED_FILE))
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fput(poll->file);
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/*
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* Drop one of our refs to this req, __io_submit_sqe() will
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* drop the other one since we're returning an error.
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@ -1621,6 +1536,50 @@ static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
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return ret;
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}
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static bool io_op_needs_file(const struct io_uring_sqe *sqe)
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{
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int op = READ_ONCE(sqe->opcode);
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|
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switch (op) {
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case IORING_OP_NOP:
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case IORING_OP_POLL_REMOVE:
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return false;
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default:
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return true;
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}
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}
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static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
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struct io_submit_state *state, struct io_kiocb *req)
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{
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unsigned flags;
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int fd;
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|
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flags = READ_ONCE(s->sqe->flags);
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fd = READ_ONCE(s->sqe->fd);
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|
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if (!io_op_needs_file(s->sqe)) {
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req->file = NULL;
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return 0;
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}
|
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|
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if (flags & IOSQE_FIXED_FILE) {
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if (unlikely(!ctx->user_files ||
|
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(unsigned) fd >= ctx->nr_user_files))
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return -EBADF;
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req->file = ctx->user_files[fd];
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req->flags |= REQ_F_FIXED_FILE;
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} else {
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if (s->needs_fixed_file)
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return -EBADF;
|
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req->file = io_file_get(state, fd);
|
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if (unlikely(!req->file))
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return -EBADF;
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}
|
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|
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return 0;
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}
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|
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static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
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struct io_submit_state *state)
|
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{
|
||||
@ -1635,6 +1594,10 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
|
||||
if (unlikely(!req))
|
||||
return -EAGAIN;
|
||||
|
||||
ret = io_req_set_file(ctx, s, state, req);
|
||||
if (unlikely(ret))
|
||||
goto out;
|
||||
|
||||
ret = __io_submit_sqe(ctx, req, s, true, state);
|
||||
if (ret == -EAGAIN) {
|
||||
struct io_uring_sqe *sqe_copy;
|
||||
@ -1664,6 +1627,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
|
||||
}
|
||||
}
|
||||
|
||||
out:
|
||||
/* drop submission reference */
|
||||
io_put_req(req);
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user