[PATCH 3.10 085/143] crypto: gcm - Fix rfc4543 decryption crash

From: Willy Tarreau
Date: Sun Jun 05 2016 - 06:22:03 EST

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: Willy Tarreau <w@xxxxxx>
crypto/gcm.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/crypto/gcm.c b/crypto/gcm.c
index b4c2520..cd97cdd 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,
+ 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);