crypto: af_alg - Set merge to zero early in af_alg_sendmsg

[ Upstream commit 9574b2330dbd2b5459b74d3b5e9619d39299fc6f ]

If an error causes af_alg_sendmsg to abort, ctx->merge may contain
a garbage value from the previous loop.  This may then trigger a
crash on the next entry into af_alg_sendmsg when it attempts to do
a merge that can't be done.

Fix this by setting ctx->merge to zero near the start of the loop.

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 15:42:41 +08:00 committed by Greg Kroah-Hartman
parent 6a075f80f3
commit 2374c11189

View File

@ -1024,6 +1024,8 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
continue;
}
ctx->merge = 0;
if (!af_alg_writable(sk)) {
err = af_alg_wait_for_wmem(sk, msg->msg_flags);
if (err)
@ -1063,7 +1065,6 @@ int af_alg_sendmsg(struct socket *sock, struct msghdr *msg, size_t size,
ctx->used += plen;
copied += plen;
size -= plen;
ctx->merge = 0;
} else {
do {
struct page *pg;