FAILED: patch "[PATCH] namei: ->d_inode of a pinned dentry is stable only for" failed to apply to 3.14-stable tree

PATCH [email protected] 1 participant 1 message Mar 1, 2016

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2016-03-01 18:47 UTC #0 lore raw

The patch below does not apply to the 3.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From d4565649b6d6923369112758212b851adc407f0c Mon Sep 17 00:00:00 2001

From: Al Viro <[email protected]>
Date: Sat, 27 Feb 2016 19:23:16 -0500
Subject: [PATCH] namei: ->d_inode of a pinned dentry is stable only for
positives

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...

Cc [email protected] # v3.13+

Signed-off-by Al Viro <[email protected]>

fs/namei.c +2 -2

index e30deefad8f8..e0881c0bd228 100644
@@ -1743,11 +1743,11 @@ static int walk_component(struct nameidata *nd, int flags)
 		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)

@@ -3192,12 +3192,12 @@ 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);