From 3a72660b07d86d60457ca32080b1ce8c2b628ee2 Mon Sep 17 00:00:00 2001 From: Jesper Nilsson Date: Thu, 21 Nov 2013 14:32:08 -0800 Subject: [PATCH] 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 --- ipc/shm.c | 9 ++++++--- 1 file 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) ipc_lock_object(&shp->shm_perm); 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; -- GitLab