[PATCH] x86/mpx: Fix off-by-one comparison with nr_registers

From: Colin King
Date: Fri Feb 26 2016 - 13:55:42 EST


From: Colin Ian King <colin.king@xxxxxxxxxxxxx>

In the unlikely event that regno == nr_registers then we get an array
overrun on regoff because the invalid register check is currently
off-by-one. Fix this with a check that regno is >= nr_registers instead.

Detected with static analysis using CoverityScan.

Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
arch/x86/mm/mpx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 5584397..8047687 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -123,7 +123,7 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
break;
}

- if (regno > nr_registers) {
+ if (regno >= nr_registers) {
WARN_ONCE(1, "decoded an instruction with an invalid register");
return -EINVAL;
}
--
2.7.0