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-rw-r--r--arch/arc/kernel/signal.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index fdd3c98dfb0f..edda76fae83f 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -131,6 +131,15 @@ SYSCALL_DEFINE0(rt_sigreturn)
/* Don't restart from sigreturn */
syscall_wont_restart(regs);
+ /*
+ * Ensure that sigreturn always returns to user mode (in case the
+ * regs saved on user stack got fudged between save and sigreturn)
+ * Otherwise it is easy to panic the kernel with a custom
+ * signal handler and/or restorer which clobberes the status32/ret
+ * to return to a bogus location in kernel mode.
+ */
+ regs->status32 |= STATUS_U_MASK;
+
return regs->r0;
badframe:
@@ -229,8 +238,11 @@ setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
/*
* handler returns using sigreturn stub provided already by userpsace
+ * If not, nuke the process right away
*/
- BUG_ON(!(ksig->ka.sa.sa_flags & SA_RESTORER));
+ if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
+ return 1;
+
regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
/* User Stack for signal handler will be above the frame just carved */
@@ -296,12 +308,12 @@ static void
handle_signal(struct ksignal *ksig, struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
- int ret;
+ int failed;
/* Set up the stack frame */
- ret = setup_rt_frame(ksig, oldset, regs);
+ failed = setup_rt_frame(ksig, oldset, regs);
- signal_setup_done(ret, ksig, 0);
+ signal_setup_done(failed, ksig, 0);
}
void do_signal(struct pt_regs *regs)