[PATCH 4.4 63/74] MIPS: traps: Fix SIGFPE information leak from `do_ov and `do_trap_or_bp

Greg Kroah-Hartman
2016-03-08T00:07:47Z

From: Maciej W. Rozycki <macro@imgtec.com>

commit e723e3f7f9591b79e8c56b3d7c5a204a9c571b55 upstream.

Avoid sending a partially initialised `siginfo_t' structure along SIGFPE
signals issued from `do_ov' and `do_trap_or_bp', leading to information
leaking from the kernel stack.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/mips/kernel/traps.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -690,15 +690,15 @@ static int simulate_sync(struct pt_regs
asmlinkage void do_ov(struct pt_regs *regs)
{
enum ctx_state prev_state;
- siginfo_t info;
+ siginfo_t info = {
+ .si_signo = SIGFPE,
+ .si_code = FPE_INTOVF,
+ .si_addr = (void __user *)regs->cp0_epc,
+ };

prev_state = exception_enter();
die_if_kernel("Integer overflow", regs);

- info.si_code = FPE_INTOVF;
- info.si_signo = SIGFPE;
- info.si_errno = 0;
- info.si_addr = (void __user *) regs->cp0_epc;
force_sig_info(SIGFPE, &info, current);
exception_exit(prev_state);
}
@@ -874,7 +874,7 @@ out:
void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
const char *str)
{
- siginfo_t info;
+ siginfo_t info = { 0 };
char b[40];

#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
@@ -903,7 +903,6 @@ void do_trap_or_bp(struct pt_regs *regs,
else
info.si_code = FPE_INTOVF;
info.si_signo = SIGFPE;
- info.si_errno = 0;
info.si_addr = (void __user *) regs->cp0_epc;
force_sig_info(SIGFPE, &info, current);
break;