Messages in this thread Patch in this message | | | Date | Tue, 09 Jun 2009 02:39:48 -0700 | From | Greg KH <> | Subject | [patch 60/87] keys: Handle there being no fallback destination keyring for request_key() |
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2.6.29-stable review patch. If anyone has any objections, please let us know.
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From: David Howells <dhowells@redhat.com>
commit 34574dd10b6d0697b86703388d6d6af9cbf4bb48 upstream.
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> Cc: Chuck Ebbert <cebbert@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- security/keys/request_key.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -311,7 +311,8 @@ static int construct_alloc_key(struct ke 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 ke 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));
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