On 6/10/24 9:52 PM, Gui-Dong Han wrote:
> In aoecmd_sleepwork, there is a race condition caused by two consecutive
> writes to the 'flags' variable within a critical section. If a read
> operation occurs between these writes, an intermediate state may be
> read, potentially causing bugs.
>
> To address this issue, the 'flags' variable should be updated in a
> single operation to ensure atomicity and prevent any intermediate state
> from being read.
>
> Fixes: 3ae1c24e395b ("[PATCH] aoe [2/8]: support dynamic resizing of AoE devices")
> Signed-off-by: Gui-Dong Han <hanguidong02@xxxxxxxxxxx>
> ---
> drivers/block/aoe/aoecmd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/block/aoe/aoecmd.c b/drivers/block/aoe/aoecmd.c
> index cc9077b588d7..37d556f019c0 100644
> --- a/drivers/block/aoe/aoecmd.c
> +++ b/drivers/block/aoe/aoecmd.c
> @@ -897,8 +897,7 @@ aoecmd_sleepwork(struct work_struct *work)
> set_capacity_and_notify(d->gd, d->ssize);
>
> spin_lock_irq(&d->lock);
> - d->flags |= DEVFL_UP;
> - d->flags &= ~DEVFL_NEWSIZE;
> + d->flags = (d->flags | DEVFL_UP) & ~DEVFL_NEWSIZE;
> spin_unlock_irq(&d->lock);
> }
It's modified under the lock, and any reader should do so as well. If
not, there's a race regardless of your change or not.
--
Jens Axboe
