From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Date: Thu, 1 Jun 2023 06:42:44 +0000 (+0800)
Subject: integrity: Fix possible multiple allocation in integrity_inode_get()
X-Git-Tag: v6.1.39~52
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=cd52323ac4c1ba42660f0478ec7a40ea92b78714;p=platform%2Fkernel%2Flinux-starfive.git

integrity: Fix possible multiple allocation in integrity_inode_get()

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>
---

diff --git a/security/integrity/iint.c b/security/integrity/iint.c
index 8638976..65418e0 100644
--- a/security/integrity/iint.c
+++ b/security/integrity/iint.c
@@ -43,12 +43,10 @@ static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
 		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_inode_get(struct inode *inode)
 		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;