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netfs: Fix AIO error handling when doing write-through

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If an error occurs whilst we're doing an AIO write in write-through mode,
we may end up calling ->ki_complete() *and* returning an error from
->write_iter().  This can result in either a UAF (the ->ki_complete() func
pointer may get overwritten, for example) or a refcount underflow in
io_submit() as ->ki_complete is called twice.

Fix this by making netfs_end_writethrough() - and thus
netfs_perform_write() - unconditionally return -EIOCBQUEUED if we're doing
an AIO write and wait for completion if we're not.

Fixes: 288ace2f57 ("netfs: New writeback implementation")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/295052.1716298587@warthog.procyon.org.uk
cc: Jeff Layton <jlayton@kernel.org>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: netfs@lists.linux.dev
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Howells 2024-05-21 14:36:27 +01:00 committed by Christian Brauner
parent 9b038d004c
commit 2c6b531020
1 changed files with 6 additions and 1 deletions
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7
fs/netfs/write_issue.c
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@ -636,7 +636,12 @@ int netfs_end_writethrough(struct netfs_io_request *wreq, struct writeback_contr
mutex_unlock(&ictx->wb_lock);
ret = wreq->error;
if (wreq->iocb) {
ret = -EIOCBQUEUED;
} else {
wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, TASK_UNINTERRUPTIBLE);
ret = wreq->error;
}
netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
return ret;
}