| From 3a72660b07d86d60457ca32080b1ce8c2b628ee2 Mon Sep 17 00:00:00 2001 |
| From: Jesper Nilsson <jesper.nilsson@axis.com> |
| Date: Thu, 21 Nov 2013 14:32:08 -0800 |
| Subject: ipc,shm: correct error return value in shmctl (SHM_UNLOCK) |
| |
| From: Jesper Nilsson <jesper.nilsson@axis.com> |
| |
| commit 3a72660b07d86d60457ca32080b1ce8c2b628ee2 upstream. |
| |
| 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 <jesper.nilsson@axis.com> |
| Cc: Davidlohr Bueso <davidlohr@hp.com> |
| Cc: Rik van Riel <riel@redhat.com> |
| Cc: Michel Lespinasse <walken@google.com> |
| Cc: Al Viro <viro@zeniv.linux.org.uk> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| ipc/shm.c | 9 ++++++--- |
| 1 file changed, 6 insertions(+), 3 deletions(-) |
| |
| --- a/ipc/shm.c |
| +++ b/ipc/shm.c |
| @@ -974,12 +974,15 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, |
| 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; |