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| author | Eric Biggers <ebiggers@google.com> | 2017-10-09 12:43:20 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-10-27 10:23:17 +0200 |
| commit | 503ef5c070a106b52fe34a04fdf02cf1f5662150 (patch) | |
| tree | c52ed0b7bc577997fef32cb0b3d4502ad995a205 /lib | |
| parent | 2b7e02267d3c8049b70fc44c410573fe0de8e6dc (diff) | |
| download | linux-stable-503ef5c070a106b52fe34a04fdf02cf1f5662150.tar.gz linux-stable-503ef5c070a106b52fe34a04fdf02cf1f5662150.tar.bz2 linux-stable-503ef5c070a106b52fe34a04fdf02cf1f5662150.zip | |
lib/digsig: fix dereference of NULL user_key_payload
commit 192cabd6a296cbc57b3d8c05c4c89d87fc102506 upstream.
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: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/digsig.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/lib/digsig.c b/lib/digsig.c index 07be6c1ef4e2..00c5c8179393 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sem); ukp = user_key_payload(key); + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + err = -EKEYREVOKED; + goto err1; + } + if (ukp->datalen < sizeof(*pkh)) goto err1; |