3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Davidlohr Bueso <[email protected]> commit c97cb9ccab8c85428ec21eff690642ad2ce1fa8a upstream. While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire it unnecessarily. We can do the permissions and security checks only holding the rcu lock. [[email protected]: coding-style fixes] Signed-off-by: Davidlohr Bueso <[email protected]> Tested-by: Sedat Dilek <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Manfred Spraul <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Cc: Mike Galbraith <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- ipc/shm.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) --- a/ipc/shm.c +++ b/ipc/shm.c @@ -882,27 +882,31 @@ static int shmctl_nolock(struct ipc_name struct shmid64_ds tbuf; int result; + rcu_read_lock(); if (cmd == SHM_STAT) { - shp = shm_lock(ns, shmid); + shp = shm_obtain_object(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); - goto out; + goto out_unlock; } result = shp->shm_perm.id; } else { - shp = shm_lock_check(ns, shmid); + shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); - goto out; + goto out_unlock; } result = 0; } + err = -EACCES; if (ipcperms(ns, &shp->shm_perm, S_IRUGO)) goto out_unlock; + err = security_shm_shmctl(shp, cmd); if (err) goto out_unlock; + memset(&tbuf, 0, sizeof(tbuf)); kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm); tbuf.shm_segsz = shp->shm_segsz; @@ -912,8 +916,9 @@ static int shmctl_nolock(struct ipc_name tbuf.shm_cpid = shp->shm_cprid; tbuf.shm_lpid = shp->shm_lprid; tbuf.shm_nattch = shp->shm_nattch; - shm_unlock(shp); - if(copy_shmid_to_user (buf, &tbuf, version)) + rcu_read_unlock(); + + if (copy_shmid_to_user(buf, &tbuf, version)) err = -EFAULT; else err = result; @@ -924,7 +929,7 @@ static int shmctl_nolock(struct ipc_name } out_unlock: - shm_unlock(shp); + rcu_read_unlock(); out: return err; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
