On Mon, Mar 05, 2018 at 07:02:45AM +0100, Greg Kroah-Hartman wrote:
On Mon, Mar 05, 2018 at 12:37:59AM +0000, Ben Hutchings wrote:
On Thu, 2018-02-15 at 16:16 +0100, Greg Kroah-Hartman wrote:
4.4-stable review patch. If anyone has any objections, please let me know.
From: Al Viro viro@zeniv.linux.org.uk
commit 21fc61c73c3903c4c312d0802da01ec2b323d174 upstream.
kmap() in page_follow_link_light() needed to go - allowing to hold an arbitrary number of kmaps for long is a great way to deadlocking the system.
new helper (inode_nohighmem(inode)) needs to be used for pagecache symlinks inodes; done for all in-tree cases. page_follow_link_light() instrumented to yell about anything missed.
Except that this backport only updates ext4 and f2fs (and doesn't add the warning). I suppose that's all matters for Android, but it would be nice to get a more complete backport into 4.4-stable...
That should be all the in-tree users of this, for 4.4, right? If not, ick. Jin, can you look into this?
thanks,
greg k-h
This was discussed already; see https://patchwork.kernel.org/patch/10203819/. It turns out that Al's original commit incidentally fixed symlink decryption for ext4 and f2fs on 32-bit systems, so the backport is wanted for that reason. And pulling in the rest of the commit, while it could be done, would have broken things and required additional follow-on patches. Jin and Greg, it would have been helpful if the discussion had been captured in the commit message, so that people like Ben who are watching the stable commits aren't left wondering.
Eric