| Message ID | ME3P282MB3617DAD141ACDD21170355E0C0C72@ME3P282MB3617.AUSP282.PROD.OUTLOOK.COM (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | aoe: consolidate flags update to prevent race condition | expand |
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@outlook.com> > --- > 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.
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); } }
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@outlook.com> --- drivers/block/aoe/aoecmd.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)