[ARM] Add code to prevent system calls from being restarted muliple times before...

Fixes crashes with thumb syscalls.

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 907d5a620bca2655a68a29fa004bc9445ae78543..15c46d27ca279d62bcc70dcc9061d353571fd556 100644 (file)
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -602,6 +602,14 @@ setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 
 static inline void setup_syscall_restart(struct pt_regs *regs)
 {
+       if (regs->ARM_ORIG_r0 == -ERESTARTNOHAND ||
+           regs->ARM_ORIG_r0 == -ERESTARTSYS ||
+           regs->ARM_ORIG_r0 == -ERESTARTNOINTR ||
+           regs->ARM_ORIG_r0 == -ERESTART_RESTARTBLOCK) {
+               /* the syscall cannot be safely restarted, return -EINTR instead */
+               regs->ARM_r0 = -EINTR;
+               return;
+       }
        regs->ARM_r0 = regs->ARM_ORIG_r0;
        regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 }
@@ -734,6 +742,7 @@ static void do_signal(struct pt_regs *regs, int syscall)
         */
        if (syscall) {
                if (regs->ARM_r0 == -ERESTART_RESTARTBLOCK) {
+                       regs->ARM_r0 = -EAGAIN; /* prevent multiple restarts */
                        if (thumb_mode(regs)) {
                                regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE;
                                regs->ARM_pc -= 2;