Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 23/32] KEYS: close race between key lookup and freeing | Date | Tue, 27 Jan 2015 17:26:53 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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From: Sasha Levin <sasha.levin@oracle.com>
commit a3a8784454692dd72e5d5d34dcdab17b4420e74c upstream.
When a key is being garbage collected, it's key->user would get put before the ->destroy() callback is called, where the key is removed from it's respective tracking structures.
This leaves a key hanging in a semi-invalid state which leaves a window open for a different task to try an access key->user. An example is find_keyring_by_name() which would dereference key->user for a key that is in the process of being garbage collected (where key->user was freed but ->destroy() wasn't called yet - so it's still present in the linked list).
This would cause either a panic, or corrupt memory.
Fixes CVE-2014-9529.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- security/keys/gc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/security/keys/gc.c +++ b/security/keys/gc.c @@ -201,12 +201,12 @@ static noinline void key_gc_unused_keys( if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) atomic_dec(&key->user->nikeys); - key_user_put(key->user); - /* now throw away the key memory */ if (key->type->destroy) key->type->destroy(key); + key_user_put(key->user); + kfree(key->description); #ifdef KEY_DEBUGGING
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