From 2dab597441667d6c04451a7dcf215241ad4c74f6 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Fri, 11 Feb 2011 15:53:38 -0800 Subject: Fix possible filp_cachep memory corruption In commit 31e6b01f4183 ("fs: rcu-walk for path lookup") we started doing path lookup using RCU, which then falls back to a careful non-RCU lookup in case of problems (LOOKUP_REVAL). So do_filp_open() has this "re-do the lookup carefully" looping case. However, that means that we must not release the open-intent file data if we are going to loop around and use it once more! Fix this by moving the release of the open-intent data to the function that allocates it (do_filp_open() itself) rather than the helper functions that can get called multiple times (finish_open() and do_last()). This makes the logic for the lifetime of that field much more obvious, and avoids the possible double free. Reported-by: J. R. Okajima Acked-by: Al Viro Cc: Nick Piggin Cc: Andrew Morton Signed-off-by: Linus Torvalds --- fs/open.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'fs/open.c') diff --git a/fs/open.c b/fs/open.c index e52389e..5a2c6eb 100644 --- a/fs/open.c +++ b/fs/open.c @@ -790,6 +790,8 @@ struct file *nameidata_to_filp(struct nameidata *nd) /* Pick up the filp from the open intent */ filp = nd->intent.open.file; + nd->intent.open.file = NULL; + /* Has the filesystem initialised the file for us? */ if (filp->f_path.dentry == NULL) { path_get(&nd->path); -- cgit v1.1