From: Shuangpeng Bai Date: Thu, 6 Aug 2026 02:27:19 +0000 (-0400) Subject: eventfs: Fix use-after-free in eventfs_remove_rec() X-Git-Tag: v7.2-rc7~1^2~11 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fd73b691702170d37d66f4b0278530cea8ed419a;p=thirdparty%2Flinux.git eventfs: Fix use-after-free in eventfs_remove_rec() eventfs_remove_rec() recursively removes the child at the current loop position. After the recursive call returns, list_for_each_entry() advances by reading list.next from the removed child. If free_ei() drops the final reference, release_ei() reuses the list/rcu union to queue an SRCU callback. The child may be freed before that read. The eventfs_mutex serializes list updates, but it does not keep the removed child alive or prevent the SRCU callback from running. Use list_for_each_entry_safe() to save the next sibling before recursively removing the current child. Cc: stable@vger.kernel.org Fixes: 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts") Link: https://patch.msgid.link/20260806022719.375354-1-shuangpeng.kernel@gmail.com Signed-off-by: Shuangpeng Bai Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt --- diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 39c7a34531e8a..93bc4f83b73e3 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -822,7 +822,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry */ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) { - struct eventfs_inode *ei_child; + struct eventfs_inode *ei_child, *tmp; /* * Check recursion depth. It should never be greater than 3: @@ -835,7 +835,7 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) return; /* search for nested folders or files */ - list_for_each_entry(ei_child, &ei->children, list) + list_for_each_entry_safe(ei_child, tmp, &ei->children, list) eventfs_remove_rec(ei_child, level + 1); list_del_rcu(&ei->list);