[SRU][Q][PATCH 2/5] crypto: algif_aead - snapshot IV for async AEAD requests

[Massimiliano Pellizzer]

From: Douya Le <ldy3087146292 at gmail.com>

AF_ALG AEAD AIO requests currently use the socket-wide IV buffer during
request processing.  For async requests, later socket activity can
update that shared state before the original request has fully
completed, which can lead to inconsistent IV handling.

Snapshot the IV into per-request storage when preparing the AEAD
request, so in-flight operations no longer depend on mutable socket
state.

Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management")
Cc: stable at kernel.org
Reported-by: Yuan Tan <yuantan098 at gmail.com>
Reported-by: Yifan Wu <yifanwucs at gmail.com>
Reported-by: Juefei Pu <tomapufckgml at gmail.com>
Reported-by: Xin Liu <bird at lzu.edu.cn>
Co-developed-by: Luxing Yin <tr0jan at lzu.edu.cn>
Signed-off-by: Luxing Yin <tr0jan at lzu.edu.cn>
Tested-by: Yucheng Lu <kanolyc at gmail.com>
Signed-off-by: Douya Le <ldy3087146292 at gmail.com>
Signed-off-by: Ren Wei <n05ec at lzu.edu.cn>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
(cherry picked from commit 5aa58c3a572b3e3b6c786953339f7978b845cc52)
CVE-2026-31431
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 crypto/algif_aead.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index dda15bb05e89..c54693d18832 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -72,8 +72,10 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 	struct af_alg_ctx *ctx = ask->private;
 	struct crypto_aead *tfm = pask->private;
 	unsigned int as = crypto_aead_authsize(tfm);
+	unsigned int ivsize = crypto_aead_ivsize(tfm);
 	struct af_alg_async_req *areq;
 	struct scatterlist *rsgl_src, *tsgl_src = NULL;
+	void *iv;
 	int err = 0;
 	size_t used = 0;		/* [in]  TX bufs to be en/decrypted */
 	size_t outlen = 0;		/* [out] RX bufs produced by kernel */
@@ -125,10 +127,14 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 
 	/* Allocate cipher request for current operation. */
 	areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
-				     crypto_aead_reqsize(tfm));
+				     crypto_aead_reqsize(tfm) + ivsize);
 	if (IS_ERR(areq))
 		return PTR_ERR(areq);
 
+	iv = (u8 *)aead_request_ctx(&areq->cra_u.aead_req) +
+	     crypto_aead_reqsize(tfm);
+	memcpy(iv, ctx->iv, ivsize);
+
 	/* convert iovecs of output buffers into RX SGL */
 	err = af_alg_get_rsgl(sk, msg, flags, areq, outlen, &usedpages);
 	if (err)
@@ -187,7 +193,7 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
 
 	/* Initialize the crypto operation */
 	aead_request_set_crypt(&areq->cra_u.aead_req, tsgl_src,
-			       areq->first_rsgl.sgl.sgt.sgl, used, ctx->iv);
+			       areq->first_rsgl.sgl.sgt.sgl, used, iv);
 	aead_request_set_ad(&areq->cra_u.aead_req, ctx->aead_assoclen);
 	aead_request_set_tfm(&areq->cra_u.aead_req, tfm);
 
-- 
2.53.0