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From: Eric Biggers <ebiggers@kernel.org>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Daniel Rosenberg <drosen@google.com>,
	stable@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-f2fs-devel@lists.sourceforge.net,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-fsdevel@vger.kernel.org,
	Gabriel Krisman Bertazi <krisman@collabora.co.uk>
Subject: Re: [PATCH v2] ext4: avoid utf8_strncasecmp() with unstable name
Date: Tue, 9 Jun 2020 13:28:21 -0700	[thread overview]
Message-ID: <20200609202821.GB1105@sol.localdomain> (raw)
In-Reply-To: <20200601200543.59417-1-ebiggers@kernel.org>

On Mon, Jun 01, 2020 at 01:05:43PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> 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: b886ee3e778e ("ext4: Support case-insensitive file name lookups")
> Cc: <stable@vger.kernel.org> # v5.2+
> 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>
> ---
> 
> v2: use memcpy() + barrier() instead of a byte-by-byte copy.
> 
>  fs/ext4/dir.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)

Ted, could you take this through the ext4 tree as a fix for 5.8?
The f2fs patch has been merged already.

- Eric

      parent reply	other threads:[~2020-06-09 20:28 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-01 20:05 [PATCH v2] ext4: avoid utf8_strncasecmp() with unstable name Eric Biggers
2020-06-01 20:49 ` Andreas Dilger
2020-06-11 15:01   ` Theodore Y. Ts'o
2020-06-09 20:28 ` Eric Biggers [this message]

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