[PATCH] crypto: authencesn - Fix src offset when decrypting in-place

[Herbert Xu <herbert@gondor.apana.org.au>]

On Tue, Apr 14, 2026 at 06:52:22PM +0200, Wolfgang Walter wrote:
> Hello,
> 
> with 6.12.18 ipsec stopped working for us. After reverting commit
> 
> commit 153d5520c3f9fd62e71c7e7f9e34b59cf411e555.
> Author: Herbert Xu <herbert@gondor.apana.org.au>
> Date:   Fri Mar 27 15:04:17 2026 +0900
> 
>     crypto: authencesn - Do not place hiseq at end of dst for out-of-place
> decryption

Yes this is broken.  Please try this patch:

---8<---
The src SG list offset wasn't set properly when decrypting in-place,
fix it.

Reported-by: Wolfgang Walter <linux@stwm.de>
Fixes: e02494114ebf ("crypto: authencesn - Do not place hiseq at end of dst for out-of-place decryption")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/authencesn.c b/crypto/authencesn.c
index c0a01d738d9b..af3d584e584f 100644
--- a/crypto/authencesn.c
+++ b/crypto/authencesn.c
@@ -228,9 +228,11 @@ static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
 
 decrypt:
 
-	if (src != dst)
-		src = scatterwalk_ffwd(areq_ctx->src, src, assoclen);
 	dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
+	if (req->src == req->dst)
+		src = dst;
+	else
+		src = scatterwalk_ffwd(areq_ctx->src, src, assoclen);
 
 	skcipher_request_set_tfm(skreq, ctx->enc);
 	skcipher_request_set_callback(skreq, flags,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt