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.