digsig: add hash size comparision on signature verification
When pkcs_1_v1_5_decode_emsa() returns without error and hash sizes do
not match, hash comparision is not done and digsig_verify_rsa() returns
no error. This is a bug and this patch fixes it.
The bug was introduced in v3.3 by commit b35e286a640f ("lib/digsig:
pkcs_1_v1_5_decode_emsa cleanup").
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/digsig.c b/lib/digsig.c
index 286d558..8c0e629 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -163,9 +163,11 @@
memcpy(out1 + head, p, l);
err = pkcs_1_v1_5_decode_emsa(out1, len, mblen, out2, &len);
+ if (err)
+ goto err;
- if (!err && len == hlen)
- err = memcmp(out2, h, hlen);
+ if (len != hlen || memcmp(out2, h, hlen))
+ err = -EINVAL;
err:
mpi_free(in);