From: David Howells Date: Wed, 22 Dec 2010 16:24:13 +0000 (+0000) Subject: KEYS: Don't call up_write() if __key_link_begin() returns an error X-Git-Tag: v2.6.36.4~26 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=de79143f1a7d8bc3340d982813ccc013cca01ccc;p=karo-tx-linux.git KEYS: Don't call up_write() if __key_link_begin() returns an error commit 3fc5e98d8cf85e0d77fc597b49e9268dff67400e upstream. 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: [] 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: [] sget+0x278/0x3e7 #1: (&ret_buf->session_mutex){+.+.+.}, at: [] cifs_get_smb_ses+0x35a/0x443 [cifs] #2: (root_key_user.cons_lock){+.+.+.}, at: [] request_key_and_link+0x10a/0x3fc stack backtrace: Pid: 5769, comm: mount.cifs Not tainted 2.6.37-rc6+ #1 Call Trace: [] ? request_key_and_link+0x263/0x3fc [] print_unlock_inbalance_bug+0xca/0xd5 [] lock_release_non_nested+0xc1/0x263 [] ? request_key_and_link+0x263/0x3fc [] ? request_key_and_link+0x263/0x3fc [] lock_release+0x17d/0x1a4 [] up_write+0x23/0x3b [] request_key_and_link+0x263/0x3fc [] ? cifs_get_spnego_key+0x61/0x21f [cifs] [] request_key+0x41/0x74 [] cifs_get_spnego_key+0x200/0x21f [cifs] [] CIFS_SessSetup+0x55d/0x1273 [cifs] [] cifs_setup_session+0x90/0x1ae [cifs] [] cifs_get_smb_ses+0x37f/0x443 [cifs] [] cifs_mount+0x1aa1/0x23f3 [cifs] [] ? alloc_debug_processing+0xdb/0x120 [] ? cifs_get_spnego_key+0x1ef/0x21f [cifs] [] cifs_do_mount+0x165/0x2b3 [cifs] [] vfs_kern_mount+0xaf/0x1dc [] do_kern_mount+0x4d/0xef [] do_mount+0x6f4/0x733 [] sys_mount+0x88/0xc2 [] system_call_fastpath+0x16/0x1b Reported-by: Jeff Layton Signed-off-by: David Howells Reviewed-and-Tested-by: Jeff Layton Signed-off-by: Linus Torvalds Cc: James Morris Signed-off-by: Greg Kroah-Hartman --- diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 0088dd8bf68a..0ea52d25a6bd 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -403,7 +403,6 @@ link_check_failed: return ret; link_prealloc_failed: - up_write(&dest_keyring->sem); mutex_unlock(&user->cons_lock); kleave(" = %d [prelink]", ret); return ret;