On Fri, Jun 19, 2020 at 04:06:23PM +0200, gregkh@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From fc3bb095ab02b9e7d89a069ade2cead15c64c504 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx> # v5.4+
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Daniel Rosenberg <drosen@xxxxxxxxxx>
Cc: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Reviewed-by: Chao Yu <yuchao0@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
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
