ARM: 5793/1: ARM: Check put_user fail in do_signal when enable OABI_COMPAT

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.

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

Signed-off-by: janboe <janboe.ye at gmail.com>
Signed-off-by: Jean Pihet <jpihet@mvista.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 2a573d4fea24..e7714f367eb8 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -662,8 +662,12 @@ static void do_signal(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
                         }
                 }