[PATCH 3.12 01/76] crypto: gcm - Fix rfc4543 decryption crash

[Jiri Slaby]

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

This bug has already bee fixed upstream since 4.2.  However, it
was fixed during the AEAD conversion so no fix was backported to
the older kernels.

When we do an RFC 4543 decryption, we will end up writing the
ICV beyond the end of the dst buffer.  This should lead to a
crash but for some reason it was never noticed.

This patch fixes it by only writing back the ICV for encryption.

Fixes: d733ac90f9fe ("crypto: gcm - fix rfc4543 to handle async...")
Reported-by: Patrick Meyer <patrick.meyer@xxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 crypto/gcm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/gcm.c b/crypto/gcm.c
index 9cea4d0b6904..f0bd00b15f26 100644
--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -1173,6 +1173,9 @@ static struct aead_request *crypto_rfc4543_crypt(struct aead_request *req,
 	aead_request_set_tfm(subreq, ctx->child);
 	aead_request_set_callback(subreq, req->base.flags, crypto_rfc4543_done,
 				  req);
+	if (!enc)
+		aead_request_set_callback(subreq, req->base.flags,
+					  req->base.complete, req->base.data);
 	aead_request_set_crypt(subreq, cipher, cipher, enc ? 0 : authsize, iv);
 	aead_request_set_assoc(subreq, assoc, assoclen);
 
-- 
2.8.2