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authorEric Biggers <ebiggers@google.com>2017-10-09 12:43:20 -0700
committerDavid Howells <dhowells@redhat.com>2017-10-12 17:16:40 +0100
commit192cabd6a296cbc57b3d8c05c4c89d87fc102506 (patch)
tree493588074de865f887e0e4e4e5932de7fd82386f
parentd124b2c53c7bee6569d2a2d0b18b4a1afde00134 (diff)
lib/digsig: fix dereference of NULL user_key_payload
digsig_verify() requests a user key, then accesses its payload. However, a revoked key has a NULL payload, and we failed to check for this. request_key() *does* skip revoked keys, but there is still a window where the key can be revoked before we acquire its semaphore. Fix it by checking for a NULL payload, treating it like a key which was already revoked at the time it was requested. Fixes: 051dbb918c7f ("crypto: digital signature verification support") Reviewed-by: James Morris <james.l.morris@oracle.com> Cc: <stable@vger.kernel.org> [v3.3+] Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
-rw-r--r--lib/digsig.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/digsig.c b/lib/digsig.c
index 03d7c63837ae..6ba6fcd92dd1 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -87,6 +87,12 @@ static int digsig_verify_rsa(struct key *key,
down_read(&key->sem);
ukp = user_key_payload_locked(key);
+ if (!ukp) {
+ /* key was revoked before we acquired its semaphore */
+ err = -EKEYREVOKED;
+ goto err1;
+ }
+
if (ukp->datalen < sizeof(*pkh))
goto err1;