From: Ted Ts'o <tytso@mit.edu>
To: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Tao Ma <tm@tao.ma>,
linux-ext4@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/5] ext4: Prevent stack overrun in ext4_file_open when recording last known mountpoint
Date: Tue, 25 Oct 2011 09:22:56 -0400 [thread overview]
Message-ID: <20111025132256.GK31921@thunk.org> (raw)
In-Reply-To: <20111021211818.10784.77127.stgit@elm3c44.beaverton.ibm.com>
On Fri, Oct 21, 2011 at 02:18:18PM -0700, Darrick J. Wong wrote:
> In ext4_file_open, the filesystem records the mountpoint of the first file that
> is opened after mounting the filesystem. It does this by allocating a 64-byte
> stack buffer, calling d_path() to grab the mount point through which this file
> was accessed, and then memcpy()ing 64 bytes into the superblock's
> s_last_mounted field, starting from the return value of d_path(), which is
> stored as "cp". However, if cp > buf (which it frequently is since path
> components are prepended starting at the end of buf) then we can end up copying
> stack data into the superblock.
>
> Writing stack variables into the superblock doesn't sound like a great idea, so
> use strlcpy instead. Andi Kleen suggested using strlcpy instead of strncpy.
>
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Thanks, applied.
- Ted
next prev parent reply other threads:[~2011-10-25 13:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-21 21:17 [PATCH 1/5] ext4: ext4_dx_add_entry should dirty directory metadata with the directory inode Darrick J. Wong
2011-10-21 21:18 ` [PATCH 2/5] ext4: ext4_rename should dirty dir_bh with the correct directory Darrick J. Wong
2011-10-25 13:08 ` Ted Ts'o
2011-10-21 21:18 ` [PATCH 3/5] ext4: ext4_mkdir should dirty dir_block with the parent inode Darrick J. Wong
2011-10-25 13:09 ` Ted Ts'o
2011-10-21 21:18 ` [PATCH 4/5] ext4: Prevent stack overrun in ext4_file_open when recording last known mountpoint Darrick J. Wong
2011-10-25 13:22 ` Ted Ts'o [this message]
2011-10-21 21:18 ` [PATCH 5/5] ext4: Fix endian problem in MMP initialization Darrick J. Wong
2011-10-22 17:25 ` Andreas Dilger
2011-10-25 13:35 ` Ted Ts'o
2011-10-25 13:13 ` [PATCH 1/5] ext4: ext4_dx_add_entry should dirty directory metadata with the directory inode Ted Ts'o
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