4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
commit d4565649b6d6923369112758212b851adc407f0c upstream.
both do_last() and walk_component() risk picking a NULL inode out
of dentry about to become positive, *then* checking its flags and
seeing that it's not negative anymore and using (already stale by
then) value they'd fetched earlier. Usually ends up oopsing soon
after that...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/namei.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1742,11 +1742,11 @@ static int walk_component(struct nameida
if (err < 0)
return err;
- inode = d_backing_inode(path.dentry);
seq = 0; /* we are already out of RCU mode */
err = -ENOENT;
if (d_is_negative(path.dentry))
goto out_path_put;
+ inode = d_backing_inode(path.dentry);
}
if (flags & WALK_PUT)
@@ -3130,12 +3130,12 @@ retry_lookup:
return error;
BUG_ON(nd->flags & LOOKUP_RCU);
- inode = d_backing_inode(path.dentry);
seq = 0; /* out of RCU mode, so the value doesn't matter */
if (unlikely(d_is_negative(path.dentry))) {
path_to_nameidata(&path, nd);
return -ENOENT;
}
+ inode = d_backing_inode(path.dentry);
finish_lookup:
if (nd->depth)
put_link(nd);
--
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