[PATCH 3.2 06/46] crypto: gcm - Fix rfc4543 decryption crash

[Ben Hutchings]

3.2.81-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 crypto/gcm.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/crypto/gcm.c
+++ b/crypto/gcm.c
@@ -1176,6 +1176,9 @@ static struct aead_request *crypto_rfc45
 	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);