[PATCH 6.4 739/800] integrity: Fix possible multiple allocation in integrity_inode_get()

Greg Kroah-Hartman
2023-07-16T20:27:23Z

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;
}

/*
@@ -113,10 +111,15 @@ 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;