From: Tianjia Zhang tianjia.zhang@linux.alibaba.com
commit 9df6a4870dc371136e90330cfbbc51464ee66993 upstream.
When integrity_inode_get() is querying and inserting the cache, there is a conditional race in the concurrent environment.
The race condition is the result of not properly implementing "double-checked locking". In this case, it first checks to see if the iint cache record exists before taking the lock, but doesn't check again after taking the integrity_iint_lock.
Fixes: bf2276d10ce5 ("ima: allocating iint improvements") Signed-off-by: Tianjia Zhang tianjia.zhang@linux.alibaba.com Cc: Dmitry Kasatkin dmitry.kasatkin@gmail.com Cc: stable@vger.kernel.org # v3.10+ Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/integrity/iint.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
--- a/security/integrity/iint.c +++ b/security/integrity/iint.c @@ -43,12 +43,10 @@ static struct integrity_iint_cache *__in else if (inode > iint->inode) n = n->rb_right; else - break; + return iint; } - if (!n) - return NULL;
- return iint; + return NULL; }
/* @@ -121,10 +119,15 @@ struct integrity_iint_cache *integrity_i parent = *p; test_iint = rb_entry(parent, struct integrity_iint_cache, rb_node); - if (inode < test_iint->inode) + if (inode < test_iint->inode) { p = &(*p)->rb_left; - else + } else if (inode > test_iint->inode) { p = &(*p)->rb_right; + } else { + write_unlock(&integrity_iint_lock); + kmem_cache_free(iint_cache, iint); + return test_iint; + } }
iint->inode = inode;