From cf4ef7801a8c880902a07712ba7ff61d8e954f85 Mon Sep 17 00:00:00 2001 From: Stanislav Goriainov Date: Wed, 31 Aug 2022 11:06:58 +0300 Subject: [PATCH] ovl: Add comment on upperredirect reassignment If memory for uperredirect was allocated with kstrdup() in upperdir != NULL and d.redirect != NULL path, it may seem that it can be lost when upperredirect is reassigned later, but it's not possible. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 0a2d0d3f2f291 ("ovl: Check redirect on index as well") Signed-off-by: Stanislav Goriainov Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 0ce1f9b3a0467..46753134533a1 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -1086,6 +1086,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, .mnt = ovl_upper_mnt(ofs), }; + /* + * It's safe to assign upperredirect here: the previous + * assignment of happens only if upperdentry is non-NULL, and + * this one only if upperdentry is NULL. + */ upperredirect = ovl_get_redirect_xattr(ofs, &upperpath, 0); if (IS_ERR(upperredirect)) { err = PTR_ERR(upperredirect); -- 2.30.2