From 4d50e8360edbef8a94a301fa4d062685e9f64a0b Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 19 Sep 2025 17:03:51 +0200 Subject: [PATCH] statmount: don't call path_put() under namespace semaphore commit e8c84e2082e69335f66c8ade4895e80ec270d7c4 upstream. Massage statmount() and make sure we don't call path_put() under the namespace semaphore. If we put the last reference we're fscked. Fixes: 46eae99ef733 ("add statmount(2) syscall") Cc: stable@vger.kernel.org # v6.8+ Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman --- fs/namespace.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 51f77c65c0c6..1d518fc5509a 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5711,7 +5711,6 @@ static int grab_requested_root(struct mnt_namespace *ns, struct path *root) static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, struct mnt_namespace *ns) { - struct path root __free(path_put) = {}; struct mount *m; int err; @@ -5723,7 +5722,7 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!s->mnt) return -ENOENT; - err = grab_requested_root(ns, &root); + err = grab_requested_root(ns, &s->root); if (err) return err; @@ -5732,7 +5731,7 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, * mounts to show users. */ m = real_mount(s->mnt); - if (!is_path_reachable(m, m->mnt.mnt_root, &root) && + if (!is_path_reachable(m, m->mnt.mnt_root, &s->root) && !ns_capable_noaudit(ns->user_ns, CAP_SYS_ADMIN)) return -EPERM; @@ -5740,8 +5739,6 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (err) return err; - s->root = root; - /* * Note that mount properties in mnt->mnt_flags, mnt->mnt_idmap * can change concurrently as we only hold the read-side of the @@ -5963,6 +5960,7 @@ retry: if (!ret) ret = copy_statmount_to_user(ks); kvfree(ks->seq.buf); + path_put(&ks->root); if (retry_statmount(ret, &seq_size)) goto retry; return ret;