[PATCH] statmount: Fix the null-ptr-deref in do_statmount()
From: Qing Wang
Date: Fri Feb 13 2026 - 03:44:07 EST
If the mount is internal, it's mnt_ns will be MNT_NS_INTERNAL, which is
defined as ERR_PTR(-EINVAL). So, in the do_statmount(), need to check ns
of mount by IS_ERR_OR_NULL().
Fixes: 0e5032237ee5 ("statmount: accept fd as a parameter")
Reported-by: syzbot+9e03a9535ea65f687a44@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/all/698e287a.a70a0220.2c38d7.009e.GAE@xxxxxxxxxx/
Tested-by: syzbot+9e03a9535ea65f687a44@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Qing Wang <wangqing7171@xxxxxxxxx>
---
fs/namespace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index a67cbe42746d..d769d50de5d6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5678,13 +5678,15 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
s->mnt = mnt_file->f_path.mnt;
ns = real_mount(s->mnt)->mnt_ns;
- if (!ns)
+ if (IS_ERR_OR_NULL(ns)) {
/*
* We can't set mount point and mnt_ns_id since we don't have a
* ns for the mount. This can happen if the mount is unmounted
- * with MNT_DETACH.
+ * with MNT_DETACH or if it's an internal mount.
*/
s->mask &= ~(STATMOUNT_MNT_POINT | STATMOUNT_MNT_NS_ID);
+ ns = NULL;
+ }
} else {
/* Has the namespace already been emptied? */
if (mnt_ns_id && mnt_ns_empty(ns))
--
2.34.1