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authorDavid Howells <dhowells@redhat.com>2009-04-09 17:14:05 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-09 10:41:19 -0700
commit34574dd10b6d0697b86703388d6d6af9cbf4bb48 (patch)
tree89eb52c0777687d4704d3ab3a370c50c1fe9479c /security
parent11ff5f6affe9b75f115a900a5584db339d46002b (diff)
downloadlinux-linaro-stable-34574dd10b6d0697b86703388d6d6af9cbf4bb48.tar.gz
keys: Handle there being no fallback destination keyring for request_key()
When request_key() is called, without there being any standard process keyrings on which to fall back if a destination keyring is not specified, an oops is liable to occur when construct_alloc_key() calls down_write() on dest_keyring's semaphore. Due to function inlining this may be seen as an oops in down_write() as called from request_key_and_link(). This situation crops up during boot, where request_key() is called from within the kernel (such as in CIFS mounts) where nobody is actually logged in, and so PAM has not had a chance to create a session keyring and user keyrings to act as the fallback. To fix this, make construct_alloc_key() not attempt to cache a key if there is no fallback key if no destination keyring is given specifically. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/keys/request_key.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 22a31582bfaa..03fe63ed55bd 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -311,7 +311,8 @@ static int construct_alloc_key(struct key_type *type,
set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
- down_write(&dest_keyring->sem);
+ if (dest_keyring)
+ down_write(&dest_keyring->sem);
/* attach the key to the destination keyring under lock, but we do need
* to do another check just in case someone beat us to it whilst we
@@ -322,10 +323,12 @@ static int construct_alloc_key(struct key_type *type,
if (!IS_ERR(key_ref))
goto key_already_present;
- __key_link(dest_keyring, key);
+ if (dest_keyring)
+ __key_link(dest_keyring, key);
mutex_unlock(&key_construction_mutex);
- up_write(&dest_keyring->sem);
+ if (dest_keyring)
+ up_write(&dest_keyring->sem);
mutex_unlock(&user->cons_lock);
*_key = key;
kleave(" = 0 [%d]", key_serial(key));