path: root/ipc/shm.c
diff options
authorJesper Nilsson <>2013-11-21 14:32:08 -0800
committerLinus Torvalds <>2013-11-21 16:42:28 -0800
commit3a72660b07d86d60457ca32080b1ce8c2b628ee2 (patch)
treeedc6f42a551b165943c4590389482c70d6f6639f /ipc/shm.c
parentb7a9f420ed737cb7cd4075ba06ac1a6f0da9f878 (diff)
ipc,shm: correct error return value in shmctl (SHM_UNLOCK)
Commit 2caacaa82a51 ("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: Jesper Nilsson <> Cc: Davidlohr Bueso <> Cc: Rik van Riel <> Cc: Michel Lespinasse <> Cc: Al Viro <> Cc: <> [3.12.x] Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'ipc/shm.c')
1 files changed, 6 insertions, 3 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 0bdf21c6814e..7a51443a51d6 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -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;