| From | Greg Kroah-Hartman <> | Subject | [PATCH 3.10 11/80] ipc,shm: correct error return value in shmctl (SHM_UNLOCK) | Date | Tue, 26 Nov 2013 16:56:40 -0800 |
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3.10-stable review patch. If anyone has any objections, please let me know.
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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;
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