5.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jiawei Ye <jiawei.ye@xxxxxxxxxxx>
[ Upstream commit 2749749afa071f8a0e405605de9da615e771a7ce ]
In the `smk_set_cipso` function, the `skp->smk_netlabel.attr.mls.cat`
field is directly assigned to a new value without using the appropriate
RCU pointer assignment functions. According to RCU usage rules, this is
illegal and can lead to unpredictable behavior, including data
inconsistencies and impossible-to-diagnose memory corruption issues.
This possible bug was identified using a static analysis tool developed
by myself, specifically designed to detect RCU-related issues.
To address this, the assignment is now done using rcu_assign_pointer(),
which ensures that the pointer assignment is done safely, with the
necessary memory barriers and synchronization. This change prevents
potential RCU dereference issues by ensuring that the `cat` field is
safely updated while still adhering to RCU's requirements.
Fixes: 0817534ff9ea ("smackfs: Fix use-after-free in netlbl_catmap_walk()")
Signed-off-by: Jiawei Ye <jiawei.ye@xxxxxxxxxxx>
Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
security/smack/smackfs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index 8403c91a6b297..44f0b5148a5b9 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -920,7 +920,7 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
rc = smk_netlbl_mls(maplevel, mapcatset, &ncats, SMK_CIPSOLEN);
if (rc >= 0) {
old_cat = skp->smk_netlabel.attr.mls.cat;
- skp->smk_netlabel.attr.mls.cat = ncats.attr.mls.cat;
+ rcu_assign_pointer(skp->smk_netlabel.attr.mls.cat, ncats.attr.mls.cat);
skp->smk_netlabel.attr.mls.lvl = ncats.attr.mls.lvl;
synchronize_rcu();
netlbl_catmap_free(old_cat);
--
2.43.0
