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linux/security/keys
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David Howells 3fc5e98d8c KEYS: Don't call up_write() if __key_link_begin() returns an error 
In construct_alloc_key(), up_write() is called in the error path if
__key_link_begin() fails, but this is incorrect as __key_link_begin() only
returns with the nominated keyring locked if it returns successfully.

Without this patch, you might see the following in dmesg:

	=====================================
	[ BUG: bad unlock balance detected! ]
	-------------------------------------
	mount.cifs/5769 is trying to release lock (&key->sem) at:
	[<ffffffff81201159>] request_key_and_link+0x263/0x3fc
	but there are no more locks to release!

	other info that might help us debug this:
	3 locks held by mount.cifs/5769:
	 #0:  (&type->s_umount_key#41/1){+.+.+.}, at: [<ffffffff81131321>] sget+0x278/0x3e7
	 #1:  (&ret_buf->session_mutex){+.+.+.}, at: [<ffffffffa0258e59>] cifs_get_smb_ses+0x35a/0x443 [cifs]
	 #2:  (root_key_user.cons_lock){+.+.+.}, at: [<ffffffff81201000>] request_key_and_link+0x10a/0x3fc

	stack backtrace:
	Pid: 5769, comm: mount.cifs Not tainted 2.6.37-rc6+ #1
	Call Trace:
	 [<ffffffff81201159>] ? request_key_and_link+0x263/0x3fc
	 [<ffffffff81081601>] print_unlock_inbalance_bug+0xca/0xd5
	 [<ffffffff81083248>] lock_release_non_nested+0xc1/0x263
	 [<ffffffff81201159>] ? request_key_and_link+0x263/0x3fc
	 [<ffffffff81201159>] ? request_key_and_link+0x263/0x3fc
	 [<ffffffff81083567>] lock_release+0x17d/0x1a4
	 [<ffffffff81073f45>] up_write+0x23/0x3b
	 [<ffffffff81201159>] request_key_and_link+0x263/0x3fc
	 [<ffffffffa026fe9e>] ? cifs_get_spnego_key+0x61/0x21f [cifs]
	 [<ffffffff812013c5>] request_key+0x41/0x74
	 [<ffffffffa027003d>] cifs_get_spnego_key+0x200/0x21f [cifs]
	 [<ffffffffa026e296>] CIFS_SessSetup+0x55d/0x1273 [cifs]
	 [<ffffffffa02589e1>] cifs_setup_session+0x90/0x1ae [cifs]
	 [<ffffffffa0258e7e>] cifs_get_smb_ses+0x37f/0x443 [cifs]
	 [<ffffffffa025a9e3>] cifs_mount+0x1aa1/0x23f3 [cifs]
	 [<ffffffff8111fd94>] ? alloc_debug_processing+0xdb/0x120
	 [<ffffffffa027002c>] ? cifs_get_spnego_key+0x1ef/0x21f [cifs]
	 [<ffffffffa024cc71>] cifs_do_mount+0x165/0x2b3 [cifs]
	 [<ffffffff81130e72>] vfs_kern_mount+0xaf/0x1dc
	 [<ffffffff81131007>] do_kern_mount+0x4d/0xef
	 [<ffffffff811483b9>] do_mount+0x6f4/0x733
	 [<ffffffff8114861f>] sys_mount+0x88/0xc2
	 [<ffffffff8100ac42>] system_call_fastpath+0x16/0x1b

Reported-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-and-Tested-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2010-12-23 15:31:48 -08:00
..
Makefile KEYS: Add garbage collection for dead, revoked and expired keys. [try #6] 2009-09-02 21:29:11 +10:00
compat.c KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] 2009-09-02 21:29:22 +10:00
gc.c KEYS: Fix RCU handling in key_gc_keyring() 2010-05-05 11:39:23 +10:00
internal.h Add a dummy printk function for the maintenance of unused printks 2010-08-12 09:51:35 -07:00
key.c KEYS: Do preallocation for __key_link() 2010-05-06 22:25:02 +10:00
keyctl.c KEYS: Fix bug in keyctl_session_to_parent() if parent has no session keyring 2010-09-10 07:30:00 -07:00
keyring.c kernel-wide: replace USHORT_MAX, SHORT_MAX and SHORT_MIN with USHRT_MAX, SHRT_MAX and SHRT_MIN 2010-05-25 08:07:02 -07:00
permission.c security: whitespace coding style fixes 2010-04-23 10:10:23 +10:00
proc.c KEYS: Make /proc/keys check to see if a key is possessed before security check 2010-08-02 15:34:27 +10:00
process_keys.c Fix install_process_keyring error handling 2010-10-28 09:02:15 -07:00
request_key.c KEYS: Don't call up_write() if __key_link_begin() returns an error 2010-12-23 15:31:48 -08:00
request_key_auth.c CRED: Inaugurate COW credentials 2008-11-14 10:39:23 +11:00
sysctl.c sysctl: Drop & in front of every proc_handler. 2009-11-18 08:37:40 -08:00
user_defined.c KEYS: Fix an RCU warning in the reading of user keys 2010-05-05 11:38:52 +10:00