[PATCH 3.12 34/58] MIPS: traps: Fix SIGFPE information leak from `do_ov' and `do_trap_or_bp'

[Jiri Slaby]

From: "Maciej W. Rozycki" <ma...@imgtec.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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 <ma...@imgtec.com>
Signed-off-by: Ralf Baechle <r...@linux-mips.org>
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
---
 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 524841f02803..45c2cb00e180 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -681,15 +681,15 @@ 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);
 }
@@ -790,7 +790,7 @@ out:
 static 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
@@ -817,7 +817,6 @@ static 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;
-- 
2.7.3