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SubjectRe: [PATCH] sysfs: Fix null pointer dereference caused by sysfs_notify on binary attribute
On Thu, Jun 06, 2013 at 10:45:20AM +0100, Nick Dyer wrote:
> If sysfs_notify is called on a binary attribute, bad things can
> happen, so prevent it.
>
> Note, no in-kernel usage of this is currently present, but in the
> future, it's good to be safe.
>
> Signed-off-by: Nick Dyer <nick.dyer@itdev.co.uk>
> ---
> fs/sysfs/file.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index 602f56d..976819b 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -449,10 +449,12 @@ void sysfs_notify_dirent(struct sysfs_dirent *sd)
>
> spin_lock_irqsave(&sysfs_open_dirent_lock, flags);
>
> - od = sd->s_attr.open;
> - if (od) {
> - atomic_inc(&od->event);
> - wake_up_interruptible(&od->poll);
> + if (sd->s_attr) {
> + od = sd->s_attr.open;
> + if (od) {
> + atomic_inc(&od->event);
> + wake_up_interruptible(&od->poll);
> + }

Please test build your patches, it makes kernel maintainers very grumpy
when you send them patches that are obviously broken :(

greg k-h


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