From 0d6ec079d6aaa098b978d6395973bb027c752a03 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Mon, 30 Oct 2017 21:14:55 +0100 Subject: [PATCH] fsnotify: pin both inode and vfsmount mark We may fail to pin one of the marks in fsnotify_prepare_user_wait() when dropping the srcu read lock, resulting in use after free at the next iteration. Solution is to store both marks in iter_info instead of just the one we'll be sending the event for. Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi Fixes: 9385a84d7e1f ("fsnotify: Pass fsnotify_iter_info into handle_event handler") Cc: # v4.12 Signed-off-by: Jan Kara --- fs/notify/fsnotify.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index 0c4583b61717..074716293829 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -335,6 +335,13 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, struct fsnotify_mark, obj_list); vfsmount_group = vfsmount_mark->group; } + /* + * Need to protect both marks against freeing so that we can + * continue iteration from this place, regardless of which mark + * we actually happen to send an event for. + */ + iter_info.inode_mark = inode_mark; + iter_info.vfsmount_mark = vfsmount_mark; if (inode_group && vfsmount_group) { int cmp = fsnotify_compare_groups(inode_group, @@ -348,9 +355,6 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, } } - iter_info.inode_mark = inode_mark; - iter_info.vfsmount_mark = vfsmount_mark; - ret = send_to_group(to_tell, inode_mark, vfsmount_mark, mask, data, data_is, cookie, file_name, &iter_info);