[PATCH 6.19 070/311] crypto: authencesn - Do not place hiseq at end of dst for out-of-place decryption

Greg Kroah-Hartman
2026-04-08T18:54:11Z

From: Herbert Xu <herbert@gondor.apana.org.au>

[ Upstream commit e02494114ebf7c8b42777c6cd6982f113bfdbec7 ]

When decrypting data that is not in-place (src != dst), there is
no need to save the high-order sequence bits in dst as it could
simply be re-copied from the source.

However, the data to be hashed need to be rearranged accordingly.

Reported-by: Taeyang Lee <0wn@theori.io>
Fixes: 104880a6b470 ("crypto: authencesn - Convert to new AEAD interface")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Thanks,

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
crypto/authencesn.c | 48 +++++++++++++++++++++++++++------------------
1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/crypto/authencesn.c b/crypto/authencesn.c
index 542a978663b9e..c0a01d738d9bc 100644
--- a/crypto/authencesn.c
+++ b/crypto/authencesn.c
@@ -207,6 +207,7 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
u8 *ohash = areq_ctx->tail;
unsigned int cryptlen = req->cryptlen - authsize;
unsigned int assoclen = req->assoclen;
+ struct scatterlist *src = req->src;
struct scatterlist *dst = req->dst;
u8 *ihash = ohash + crypto_ahash_digestsize(auth);
u32 tmp[2];
@@ -214,23 +215,27 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
if (!authsize)
goto decrypt;

- /* Move high-order bits of sequence number back. */
- scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
- scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
- scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
+ if (src == dst) {
+ /* Move high-order bits of sequence number back. */
+ scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
+ scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
+ scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
+ } else
+ memcpy_sglist(dst, src, assoclen);

if (crypto_memneq(ihash, ohash, authsize))
return -EBADMSG;

decrypt:

- sg_init_table(areq_ctx->dst, 2);
+ if (src != dst)
+ src = scatterwalk_ffwd(areq_ctx->src, src, assoclen);
dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);

skcipher_request_set_tfm(skreq, ctx->enc);
skcipher_request_set_callback(skreq, flags,
req->base.complete, req->base.data);
- skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
+ skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);

return crypto_skcipher_decrypt(skreq);
}
@@ -255,6 +260,7 @@ static int crypto_authenc_esn_decrypt(struct aead_request *req)
unsigned int assoclen = req->assoclen;
unsigned int cryptlen = req->cryptlen;
u8 *ihash = ohash + crypto_ahash_digestsize(auth);
+ struct scatterlist *src = req->src;
struct scatterlist *dst = req->dst;
u32 tmp[2];
int err;
@@ -262,24 +268,28 @@ static int crypto_authenc_esn_decrypt(struct aead_request *req)
if (assoclen < 8)
return -EINVAL;

- cryptlen -= authsize;
-
- if (req->src != dst)
- memcpy_sglist(dst, req->src, assoclen + cryptlen);
+ if (!authsize)
+ goto tail;

+ cryptlen -= authsize;
scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
authsize, 0);

- if (!authsize)
- goto tail;
-
/* Move high-order bits of sequence number to the end. */
- scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
- scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
- scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
-
- sg_init_table(areq_ctx->dst, 2);
- dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+ scatterwalk_map_and_copy(tmp, src, 0, 8, 0);
+ if (src == dst) {
+ scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
+ scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
+ dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+ } else {
+ scatterwalk_map_and_copy(tmp, dst, 0, 4, 1);
+ scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen - 4, 4, 1);
+
+ src = scatterwalk_ffwd(areq_ctx->src, src, 8);
+ dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
+ memcpy_sglist(dst, src, assoclen + cryptlen - 8);
+ dst = req->dst;
+ }

ahash_request_set_tfm(ahreq, auth);
ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
--
2.53.0