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This is an addendum for the 4.11 merge window. 

Andy Price wrote this patch to close a nasty race condition
 that allows access to glocks that are being destroyed. Without
 this patch, GFS2 is vulnerable to random corruption and kernel
 panic.
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Merge tag 'gfs2-4.11.addendum' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2

Pull GFS2 fix from Bob Peterson:
 "This is an addendum for the 4.11 merge window.

  Andy Price wrote this patch to close a nasty race condition that
  allows access to glocks that are being destroyed. Without this patch,
  GFS2 is vulnerable to random corruption and kernel panic"

* tag 'gfs2-4.11.addendum' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Add missing rcu locking for glock	lookup
This commit is contained in:
Linus Torvalds 2017-02-23 09:36:04 -08:00
parent 28cbc335d2 f38e5fb95a
commit 15192b0295
1 changed files with 5 additions and 0 deletions
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5
fs/gfs2/glock.c
View File

@ -658,9 +658,11 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
struct kmem_cache *cachep;
int ret, tries = 0;
rcu_read_lock();
gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
if (gl && !lockref_get_not_dead(&gl->gl_lockref))
gl = NULL;
rcu_read_unlock();
*glp = gl;
if (gl)
@ -728,15 +730,18 @@ again:
if (ret == -EEXIST) {
ret = 0;
rcu_read_lock();
tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
if (++tries < 100) {
rcu_read_unlock();
cond_resched();
goto again;
}
tmp = NULL;
ret = -ENOMEM;
}
rcu_read_unlock();
} else {
WARN_ON_ONCE(ret);
}