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crypto: af_alg - Fix race around ctx->rcvused by making it atomic_t

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This variable was increased and decreased without any protection.
Result was an occasional misscount and negative wrap around resulting
in false resource allocation failures.

Fixes: 7d2c3f54e6 ("crypto: af_alg - remove locking in async callback")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Jonathan Cameron 2017-12-19 10:27:24 +00:00 committed by Herbert Xu
parent e57121d08c
commit af955bf15d
4 changed files with 7 additions and 6 deletions
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4
crypto/af_alg.c
View File

@ -664,7 +664,7 @@ void af_alg_free_areq_sgls(struct af_alg_async_req *areq)
unsigned int i;
list_for_each_entry_safe(rsgl, tmp, &areq->rsgl_list, list) {
ctx->rcvused -= rsgl->sg_num_bytes;
atomic_sub(rsgl->sg_num_bytes, &ctx->rcvused);
af_alg_free_sg(&rsgl->sgl);
list_del(&rsgl->list);
if (rsgl != &areq->first_rsgl)
@ -1162,7 +1162,7 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
areq->last_rsgl = rsgl;
len += err;
ctx->rcvused += err;
atomic_add(err, &ctx->rcvused);
rsgl->sg_num_bytes = err;
iov_iter_advance(&msg->msg_iter, err);
}

2
crypto/algif_aead.c
View File

@ -571,7 +571,7 @@ static int aead_accept_parent_nokey(void *private, struct sock *sk)
INIT_LIST_HEAD(&ctx->tsgl_list);
ctx->len = len;
ctx->used = 0;
ctx->rcvused = 0;
atomic_set(&ctx->rcvused, 0);
ctx->more = 0;
ctx->merge = 0;
ctx->enc = 0;

2
crypto/algif_skcipher.c
View File

@ -390,7 +390,7 @@ static int skcipher_accept_parent_nokey(void *private, struct sock *sk)
INIT_LIST_HEAD(&ctx->tsgl_list);
ctx->len = len;
ctx->used = 0;
ctx->rcvused = 0;
atomic_set(&ctx->rcvused, 0);
ctx->more = 0;
ctx->merge = 0;
ctx->enc = 0;

5
include/crypto/if_alg.h
View File

@ -18,6 +18,7 @@
#include <linux/if_alg.h>
#include <linux/scatterlist.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <net/sock.h>
#include <crypto/aead.h>
@ -150,7 +151,7 @@ struct af_alg_ctx {
struct crypto_wait wait;
size_t used;
size_t rcvused;
atomic_t rcvused;
bool more;
bool merge;
@ -215,7 +216,7 @@ static inline int af_alg_rcvbuf(struct sock *sk)
struct af_alg_ctx *ctx = ask->private;
return max_t(int, max_t(int, sk->sk_rcvbuf & PAGE_MASK, PAGE_SIZE) -
ctx->rcvused, 0);
atomic_read(&ctx->rcvused), 0);
}
/**