[PATCH] check put_user fail in do_signal when enable OABI_COMPACT

[Jean Pihet]

On Wednesday 28 October 2009 17:23:01 Jean Pihet wrote:
...
> > Still wrong.  Why flush_icache?
>
> Indeed that is wrong (again!). I had put it in the problem description but
> that does not apply anymore.
>
> Thanks, will send an update.
Here is the updated patch. Is it OK?

Jean
>
> > Nicolas
>
> Jean
>

---
From 28336b68b2e2507ba0922c55147e5e72ec1a88dc Mon Sep 17 00:00:00 2001
From: Jean Pihet <jpihet at mvista.com>
Date: Tue, 27 Oct 2009 10:09:22 +0100
Subject: ARM: Check put_user fail in do_signal when enable OABI_COMPAT

Source: Janboe Ye <janboe.ye at gmail.com>
MR: 36048
Type: Defect Fix
Disposition: Submitted to linux-arm-kernel ML
ChangeID: 689ddf707d2232e9cf01387ac1264bc8812b9ffd
Description:

Using OABI, the call to put_user in do_signal can fail causing the calling
app to hang.

The solution is to check if put_user fails and force the app to
seg fault in that case.

Signed-off-by: janboe <janboe.ye at gmail.com>

Merged from
http://lists.infradead.org/pipermail/linux-arm-kernel/2009-October/002621.html
on top of
http://marc.info/?l=linux-arm-kernel&m=125638133624452&w=2

Tested with multiple sleeping apps/threads (using the nanosleep syscall) and
suspend/resume.

Signed-off-by: Jean Pihet <jpihet at mvista.com>
---
 arch/arm/kernel/signal.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index f330974..ea9722a 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -676,8 +676,12 @@ static int do_signal(sigset_t *oldset, struct pt_regs 
*regs, int syscall)
 				regs->ARM_sp -= 4;
 				usp = (u32 __user *)regs->ARM_sp;
 
-				put_user(regs->ARM_pc, usp);
-				regs->ARM_pc = KERN_RESTART_CODE;
+				if (put_user(regs->ARM_pc, usp) == 0) {
+					regs->ARM_pc = KERN_RESTART_CODE;
+				} else {
+					regs->ARM_sp += 4;
+					force_sigsegv(0, current);
+				}
 #endif
 			}
 		}
-- 
1.6.2.5.168.g3823