[PATCH] check put_user fail in do_signal when enable OABI_COMPACT

[Jean Pihet]

Nicolas,

On Tuesday 27 October 2009 19:59:36 Nicolas Pitre wrote:
...
> > Side question: does the put_user requires a flush of some sort? If not,
> > why?
>
> No because it stores data into the d-cache directly at the virtual
> address to be used by user space.  Previously the d-cache needed to
> be cleaned for data to hit main memory and the i-cache invalidated for
> the newly stored _code_ to be seen by the instruction path.  Since there
> is no code involved anymore the cache flushes are useless.
>
> > Is it OK to re-send a patch with the call to flush_icache_range removed?
>
> Yes.
Ok here is the updated patch. Let's hope it is the good one that time ;-)

Can it be merged? It applies cleanly on top of Russell's latest patch 
(http://marc.info/?l=linux-arm-kernel&m=125638133624452&w=2).
>
>
> Nicolas

Regards,
Jean

---
From d862e03679f7ea44fca1bf1ea256bbade3fbe76a 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

Using OABI, do_signal need to copy restart_syscall to user stack.
It is possible that put_user fail. This triggers flush_icache page
fault and crash kernel.

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