4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jiawei Ye jiawei.ye@foxmail.com
[ 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@foxmail.com Signed-off-by: Casey Schaufler casey@schaufler-ca.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 61e734baa332a..83dbfa26a6518 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -948,7 +948,7 @@ 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);