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

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jun 22, 2020 at 09:29:48PM -0400, Sasha Levin wrote:
> 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 for this fix, and the other fixes for the FAILED patches you have
queued up.

greg k-h