imrcpan/erofs-linux
1
0 Fork 0
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git synced 2026-10-30 22:03:17 +01:00
Code Issues Packages Projects Releases Wiki Activity

smackfs: Fix use-after-free in netlbl_catmap_walk()

Browse Source 
Syzkaller reported use-after-free bug as described in [1]. The bug is
triggered when smk_set_cipso() tries to free stale category bitmaps
while there are concurrent reader(s) using the same bitmaps.

Wait for RCU grace period to finish before freeing the category bitmaps
in smk_set_cipso(). This makes sure that there are no more readers using
the stale bitmaps and freeing them should be safe.

[1] https://lore.kernel.org/netdev/[email protected]/

Reported-by: [email protected]
Signed-off-by: Pawan Gupta <[email protected]>
Signed-off-by: Casey Schaufler <[email protected]>
This commit is contained in:
Pawan Gupta authored and Casey Schaufler committed 2021-09-15 16:42:25 -07:00
1 parent 6880fa6c56
commit 0817534ff9
1 file changed
+4 -1
Download Patch File Download Diff File Expand all files Collapse all files
security/smack/smackfs.c
+4 -1
View File
@@ -831,6 +831,7 @@ static int smk_open_cipso(struct inode *inode, struct file *file)
static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, int format)
{
struct netlbl_lsm_catmap *old_cat;
struct smack_known *skp;
struct netlbl_lsm_secattr ncats;
char mapcatset[SMK_CIPSOLEN];
@@ -920,9 +921,11 @@ 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) {
netlbl_catmap_free(skp->smk_netlabel.attr.mls.cat);
old_cat = skp->smk_netlabel.attr.mls.cat;
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);
rc = count;
/*
* This mapping may have been cached, so clear the cache.