[lkml]   [2013]   [Sep]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 4/4] ipc,msg: prevent race with rmid in msgsnd,msgrcv
Hi Andrew,

Could you include the patch in -mm and push it towards Linus?

On 09/16/2013 05:04 AM, Davidlohr Bueso wrote:
> This fixes a race in both msgrcv() and msgsnd() between finding the msg and
> actually dealing with the queue, as another thread can delete shmid
> underneath us if we are preempted before acquiring the kern_ipc_perm.lock.
> Manfred illustrates this nicely:
> Assume a preemptible kernel that is preempted just after
>> msq = msq_obtain_object_check(ns, msqid)
> in do_msgrcv().
> The only lock that is held is rcu_read_lock().
> Now the other thread processes IPC_RMID.
> When the first task is resumed, then it will happily wait for messages on a
> deleted queue.
> Fix this by checking for if the queue has been deleted after taking the lock.
> Reported-by: Manfred Spraul <>
> Cc: # for 3.11
> Signed-off-by: Davidlohr Bueso <>
Signed-off-by: Manfred Spraul <>

 \ /
  Last update: 2013-09-27 08:21    [W:0.048 / U:9.172 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site