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ipc: fix ipc data structures inconsistency

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As described in the title, this patch fixes <ipc>id_ds inconsistency when
<ipc>ctl_stat executes concurrently with some ds-changing function, e.g.
shmat, msgsnd or whatever.

For instance, if shmctl(IPC_STAT) is running concurrently
with shmat, following data structure can be returned:
{... shm_lpid = 0, shm_nattch = 1, ...}

Link: http://lkml.kernel.org/r/20171202153456.6514-1-philippe.mikoyan@skat.systems
Signed-off-by: Philippe Mikoyan <philippe.mikoyan@skat.systems>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Philippe Mikoyan
2018-02-06 15:40:49 -08:00
committed by Linus Torvalds
parent bac7a1fff7
commit 87ad4b0d85
4 changed files with 43 additions and 12 deletions
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10
ipc/sem.c
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@@ -1213,10 +1213,20 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
if (err)
goto out_unlock;
ipc_lock_object(&sma->sem_perm);
if (!ipc_valid_object(&sma->sem_perm)) {
ipc_unlock_object(&sma->sem_perm);
err = -EIDRM;
goto out_unlock;
}
kernel_to_ipc64_perm(&sma->sem_perm, &semid64->sem_perm);
semid64->sem_otime = get_semotime(sma);
semid64->sem_ctime = sma->sem_ctime;
semid64->sem_nsems = sma->sem_nsems;
ipc_unlock_object(&sma->sem_perm);
rcu_read_unlock();
return id;