Commit 3a72660b authored by Jesper Nilsson's avatar Jesper Nilsson Committed by Linus Torvalds
Browse files

ipc,shm: correct error return value in shmctl (SHM_UNLOCK)

Commit 2caacaa8

 ("ipc,shm: shorten critical region for shmctl")
restructured the ipc shm to shorten critical region, but introduced a
path where the return value could be -EPERM, even if the operation
actually was performed.

Before the commit, the err return value was reset by the return value
from security_shm_shmctl() after the if (!ns_capable(...)) statement.

Now, we still exit the if statement with err set to -EPERM, and in the
case of SHM_UNLOCK, it is not reset at all, and used as the return value
from shmctl.

To fix this, we only set err when errors occur, leaving the fallthrough
case alone.
Signed-off-by: default avatarJesper Nilsson <>
Cc: Davidlohr Bueso <>
Cc: Rik van Riel <>
Cc: Michel Lespinasse <>
Cc: Al Viro <>
Cc: <>	[3.12.x]
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent b7a9f420
......@@ -977,12 +977,15 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
kuid_t euid = current_euid();
err = -EPERM;
if (!uid_eq(euid, shp->shm_perm.uid) &&
!uid_eq(euid, shp->shm_perm.cuid))
!uid_eq(euid, shp->shm_perm.cuid)) {
err = -EPERM;
goto out_unlock0;
if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
err = -EPERM;
goto out_unlock0;
shm_file = shp->shm_file;
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