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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 7e95e1a86510..6763654239a2 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:
@@ -234,8 +243,11 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info,
/*
* handler returns using sigreturn stub provided already by userpsace
+ * If not, nuke the process right away
*/
- BUG_ON(!(ka->sa.sa_flags & SA_RESTORER));
+ if(!(ka->sa.sa_flags & SA_RESTORER))
+ return 1;
+
regs->blink = (unsigned long)ka->sa.sa_restorer;
/* User Stack for signal handler will be above the frame just carved */
@@ -302,12 +314,12 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
struct pt_regs *regs)
{
sigset_t *oldset = sigmask_to_save();
- int ret;
+ int failed;
/* Set up the stack frame */
- ret = setup_rt_frame(sig, ka, info, oldset, regs);
+ failed = setup_rt_frame(sig, ka, info, oldset, regs);
- if (ret)
+ if (failed)
force_sigsegv(sig, current);
else
signal_delivered(sig, info, ka, regs, 0);