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

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

From: Dmitry Kasatkin <dmitry.kasat...@intel.com>

commit bc01637a80f5b670bd70a0279d3f93fa8de1c96d upstream.

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").

Signed-off-by: Dmitry Kasatkin <dmitry.kasat...@intel.com>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 lib/digsig.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -163,9 +163,11 @@ static int digsig_verify_rsa(struct key
        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);


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