Re: FAILED: patch "[PATCH] f2fs: avoid utf8_strncasecmp() with unstable name" failed to apply to 5.7-stable tree

[Sasha Levin <sashal@kernel.org>]

On Fri, Jun 19, 2020 at 04:06:23PM +0200, gregkh@linuxfoundation.org wrote:
>
>The patch below does not apply to the 5.7-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 <stable@vger.kernel.org>.
>
>thanks,
>
>greg k-h
>
>------------------ original commit in Linus's tree ------------------
>
>From fc3bb095ab02b9e7d89a069ade2cead15c64c504 Mon Sep 17 00:00:00 2001
>From: Eric Biggers <ebiggers@google.com>
>Date: Mon, 1 Jun 2020 13:08:05 -0700
>Subject: [PATCH] f2fs: avoid utf8_strncasecmp() with unstable name
>
>If the dentry name passed to ->d_compare() fits in dentry::d_iname, then
>it may be concurrently modified by a rename.  This can cause undefined
>behavior (possibly out-of-bounds memory accesses or crashes) in
>utf8_strncasecmp(), since fs/unicode/ isn't written to handle strings
>that may be concurrently modified.
>
>Fix this by first copying the filename to a stack buffer if needed.
>This way we get a stable snapshot of the filename.
>
>Fixes: 2c2eb7a300cd ("f2fs: Support case-insensitive file name lookups")
>Cc: <stable@vger.kernel.org> # v5.4+
>Cc: Al Viro <viro@zeniv.linux.org.uk>
>Cc: Daniel Rosenberg <drosen@google.com>
>Cc: Gabriel Krisman Bertazi <krisman@collabora.co.uk>
>Signed-off-by: Eric Biggers <ebiggers@google.com>
>Reviewed-by: Chao Yu <yuchao0@huawei.com>
>Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

I've grabbed f874fa1c7c79 ("f2fs: split f2fs_d_compare() from
f2fs_match_name()") as a dependency and queued both for 5.7 and 5.4.

-- 
Thanks,
Sasha