[PATCH 1/2] ras: fix an off-by-one error in __find_elem()

Cong Wang
2019-04-16T01:20:20Z

ce_arr.array[] is always within the range [0, ce_arr.n-1].
However, the binary search code in __find_elem() uses ce_arr.n
as the maximum index, which could lead to an off-by-one
out-of-bound access when the element after the last is exactly
the one just got deleted, that is, 'min' returned to caller as
'ce_arr.n'.

Fixes: 011d82611172 ("RAS: Add a Corrected Errors Collector")
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
drivers/ras/cec.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index 2d9ec378a8bc..61332c9aab5a 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -184,7 +184,7 @@ static void cec_timer_fn(struct timer_list *unused)
static int __find_elem(struct ce_array *ca, u64 pfn, unsigned int *to)
{
u64 this_pfn;
- int min = 0, max = ca->n;
+ int min = 0, max = ca->n - 1;

while (min < max) {
int tmp = (max + min) >> 1;
--
2.20.1