From: Douya Le <ldy3087146292@gmail.com>
Date: Thu, 2 Apr 2026 15:34:55 +0000 (+0800)
Subject: crypto: af_alg - limit RX SG extraction by receive buffer budget
X-Git-Tag: v7.0~7^2~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8eceab19eba9dcbfd2a0daec72e1bf48aa100170;p=thirdparty%2Flinux.git

crypto: af_alg - limit RX SG extraction by receive buffer budget

Make af_alg_get_rsgl() limit each RX scatterlist extraction to the
remaining receive buffer budget.

af_alg_get_rsgl() currently uses af_alg_readable() only as a gate
before extracting data into the RX scatterlist. Limit each extraction
to the remaining af_alg_rcvbuf(sk) budget so that receive-side
accounting matches the amount of data attached to the request.

If skcipher cannot obtain enough RX space for at least one chunk while
more data remains to be processed, reject the recvmsg call instead of
rounding the request length down to zero.

Fixes: e870456d8e7c8d57c059ea479b5aadbb55ff4c3a ("crypto: algif_skcipher - overhaul memory management")
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Suggested-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Douya Le <ldy3087146292@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 8e0199394984d..437f3e77c7e0e 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1229,6 +1229,8 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
 
 		seglen = min_t(size_t, (maxsize - len),
 			       msg_data_left(msg));
+		/* Never pin more pages than the remaining RX accounting budget. */
+		seglen = min_t(size_t, seglen, af_alg_rcvbuf(sk));
 
 		if (list_empty(&areq->rsgl_list)) {
 			rsgl = &areq->first_rsgl;
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 82735e51be108..ba0a17fd95aca 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -130,6 +130,11 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
 	 * full block size buffers.
 	 */
 	if (ctx->more || len < ctx->used) {
+		if (len < bs) {
+			err = -EINVAL;
+			goto free;
+		}
+
 		len -= len % bs;
 		cflags |= CRYPTO_SKCIPHER_REQ_NOTFINAL;
 	}