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kernfs: Acquire kernfs_rwsem in kernfs_notify_workfn().

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kernfs_notify_workfn() dereferences kernfs_node::name and passes it
later to fsnotify(). If the node is renamed then the previously observed
name pointer becomes invalid.

Acquire kernfs_root::kernfs_rwsem to block renames of the node.

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20250213145023.2820193-2-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2025-02-13 15:50:18 +01:00 committed by Greg Kroah-Hartman
parent a64dcfb451
commit 400188ae36
1 changed files with 2 additions and 0 deletions
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2
fs/kernfs/file.c
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@ -911,6 +911,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
/* kick fsnotify */ /* kick fsnotify */
down_read(&root->kernfs_supers_rwsem); down_read(&root->kernfs_supers_rwsem);
down_read(&root->kernfs_rwsem);
list_for_each_entry(info, &kernfs_root(kn)->supers, node) { list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
struct kernfs_node *parent; struct kernfs_node *parent;
struct inode *p_inode = NULL; struct inode *p_inode = NULL;
@ -947,6 +948,7 @@ static void kernfs_notify_workfn(struct work_struct *work)
iput(inode); iput(inode);
} }
up_read(&root->kernfs_rwsem);
up_read(&root->kernfs_supers_rwsem); up_read(&root->kernfs_supers_rwsem);
kernfs_put(kn); kernfs_put(kn);
goto repeat; goto repeat;