[PATCH 4.2.y-ckt 68/98] MIPS: traps: Fix SIGFPE information leak from `do_ov' and `do_trap_or_bp'

Kamal Mostafa
2016-03-15T23:33:10Z

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: Kamal Mostafa <kamal@canonical.com>
---
arch/mips/kernel/traps.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 8ea28e6..ef1e9d3 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -694,15 +694,15 @@ static int simulate_sync(struct pt_regs *regs, unsigned int opcode)
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);
}
@@ -878,7 +878,7 @@ 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
@@ -906,7 +906,6 @@ void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
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;
--
2.7.0