Re: [PATCH 1/2] sysfs: fix race between readdir and lseek

From: Li Zefan
Date: Wed Mar 20 2013 - 22:41:49 EST

On 2013/3/20 23:25, Ming Lei wrote:
> While readdir() is running, lseek() may set filp->f_pos as zero,
> then may leave filp->private_data pointing to one sysfs_dirent
> object without holding its reference counter, so the sysfs_dirent
> object may be used after free in next readdir().
> This patch holds inode->i_mutex to avoid the problem since
> the lock is always held in readdir path.

In fact the same race exists between readdir() and read()/write()...

> Reported-by: Dave Jones <davej@xxxxxxxxxx>
> Tested-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
> ---
> fs/sysfs/dir.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)

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