commit: 2e4930eb7c8fb20a39dfb5f8a8f80402710dcea8
From: Kees Cook <[email protected]>
Date: Mon, 27 Aug 2012 11:38:13 -0700
Subject: Yama: handle 32-bit userspace prctl

When running a 64-bit kernel and receiving prctls from a 32-bit
userspace, the "-1" used as an unsigned long will end up being
misdetected. The kernel is looking for 0xffffffffffffffff instead of
0xffffffff. Since prctl lacks a distinct compat interface, Yama needs
to handle this translation itself. As such, support either value as
meaning PR_SET_PTRACER_ANY, to avoid breaking the ABI for 64-bit.

Signed-off-by: Kees Cook <[email protected]>
Acked-by: John Johansen <[email protected]>
Cc: [email protected]
Signed-off-by: James Morris <[email protected]>
---
 security/yama/yama_lsm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 9ca43c1..01d3b44 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -143,7 +143,7 @@ int yama_task_prctl(int option, unsigned long arg2, 
unsigned long arg3,
                if (arg2 == 0) {
                        yama_ptracer_del(NULL, myself);
                        rc = 0;
-               } else if (arg2 == PR_SET_PTRACER_ANY) {
+               } else if (arg2 == PR_SET_PTRACER_ANY || (int)arg2 == -1) {
                        rc = yama_ptracer_add(NULL, myself);
                } else {
                        struct task_struct *tracer;
-- 
1.7.3.4
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