crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg

[ Upstream commit 1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 ]

Issuing two writes to the same af_alg socket is bogus as the
data will be interleaved in an unpredictable fashion.  Furthermore,
concurrent writes may create inconsistencies in the internal
socket state.

Disallow this by adding a new ctx->write field that indiciates
exclusive ownership for writing.

Fixes: 8ff590903d ("crypto: algif_skcipher - User-space interface for skcipher operations")
Reported-by: Muhammad Alifa Ramdhan <ramdhan@starlabs.sg>
Reported-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Herbert Xu 2025-09-16 17:20:59 +08:00 committed by Greg Kroah-Hartman
parent e15de80737
commit e4c1ec1113
2 changed files with 13 additions and 4 deletions

View File

@ -862,6 +862,12 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
}
lock_sock(sk);
if (ctx->write) {
release_sock(sk);
return -EBUSY;
}
ctx->write = true;
if (ctx->init && !ctx->more) {
if (ctx->used) {
err = -EINVAL;
@ -969,6 +975,7 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
unlock:
af_alg_data_wakeup(sk);
ctx->write = false;
release_sock(sk);
return copied ?: err;

View File

@ -136,6 +136,7 @@ struct af_alg_async_req {
* SG?
* @enc: Cryptographic operation to be performed when
* recvmsg is invoked.
* @write: True if we are in the middle of a write.
* @init: True if metadata has been sent.
* @len: Length of memory allocated for this data structure.
* @inflight: Non-zero when AIO requests are in flight.
@ -151,10 +152,11 @@ struct af_alg_ctx {
size_t used;
atomic_t rcvused;
bool more;
bool merge;
bool enc;
bool init;
u32 more:1,
merge:1,
enc:1,
write:1,
init:1;
unsigned int len;