linux-stable/security
Mark Rutland 92347cfd62 KEYS: fix refcount_inc() on zero
If a key's refcount is dropped to zero between key_lookup() peeking at
the refcount and subsequently attempting to increment it, refcount_inc()
will see a zero refcount.  Here, refcount_inc() will WARN_ONCE(), and
will *not* increment the refcount, which will remain zero.

Once key_lookup() drops key_serial_lock, it is possible for the key to
be freed behind our back.

This patch uses refcount_inc_not_zero() to perform the peek and increment
atomically.

Fixes: fff292914d ("security, keys: convert key.usage from atomic_t to refcount_t")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: David Windsor <dwindsor@gmail.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hans Liljestrand <ishkamiel@gmail.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-06-09 13:29:50 +10:00
..
apparmor apparmorfs: replace CURRENT_TIME with current_time() 2017-05-08 17:15:15 -07:00
integrity Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity into next 2017-04-19 22:00:15 +10:00
keys KEYS: fix refcount_inc() on zero 2017-06-09 13:29:50 +10:00
loadpin security: mark LSM hooks as __ro_after_init 2017-03-06 11:00:15 +11:00
selinux Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
smack Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-05-09 09:12:53 -07:00
tomoyo Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-05-03 08:50:52 -07:00
yama security: mark LSM hooks as __ro_after_init 2017-03-06 11:00:15 +11:00
commoncap.c security: mark LSM hooks as __ro_after_init 2017-03-06 11:00:15 +11:00
device_cgroup.c security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition 2015-09-03 18:13:10 -07:00
inode.c fs: constify tree_descr arrays passed to simple_fill_super() 2017-04-26 23:54:06 -04:00
Kconfig Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-05-03 08:50:52 -07:00
lsm_audit.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-10-04 14:48:27 -07:00
Makefile LSM: LoadPin for kernel file loading restrictions 2016-04-21 10:47:27 +10:00
min_addr.c
security.c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2017-05-03 08:50:52 -07:00