2020-07-23 13:40:35

by Huang Guobin

Subject: [PATCH] lib: Verify array index is correct before using it

This code reads from the array before verifying that "c" is a valid
index. Move test array offset code before use to fix it.

Fixes: 2da572c959dd ("lib: add software 842 compression/decompression")
Signed-off-by: Huang Guobin <[email protected]>
---
lib/842/842_compress.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
index c02baa4168e1..10f9f8a0d05b 100644
--- a/lib/842/842_compress.c
+++ b/lib/842/842_compress.c
@@ -222,12 +222,13 @@ static int add_bits(struct sw842_param *p, u64 d, u8 n)
static int add_template(struct sw842_param *p, u8 c)
{
int ret, i, b = 0;
- u8 *t = comp_ops[c];
+ u8 *t = NULL;
bool inv = false;

if (c >= OPS_MAX)
return -EINVAL;

+ t = comp_ops[c];
pr_debug("template %x\n", t[4]);

ret = add_bits(p, t[4], OP_BITS);
@@ -379,12 +380,14 @@ static int add_end_template(struct sw842_param *p)

static bool check_template(struct sw842_param *p, u8 c)
{
- u8 *t = comp_ops[c];
+ u8 *t = NULL;
int i, match, b = 0;

if (c >= OPS_MAX)
return false;

+ t = comp_ops[c];
+
for (i = 0; i < 4; i++) {
if (t[i] & OP_ACTION_INDEX) {
if (t[i] & OP_AMOUNT_2)
--
2.17.1

2020-07-23 14:23:59

by Randy Dunlap

Subject: Re: [PATCH] lib: Verify array index is correct before using it

On 7/23/20 6:48 AM, Huang Guobin wrote:
> This code reads from the array before verifying that "c" is a valid
> index. Move test array offset code before use to fix it.
>
> Fixes: 2da572c959dd ("lib: add software 842 compression/decompression")
> Signed-off-by: Huang Guobin <[email protected]>

Hi,
Why shouldn't these locations use array_index_nospec() from
#include <linux/nospec.h>
?


> ---
> lib/842/842_compress.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
> index c02baa4168e1..10f9f8a0d05b 100644
> --- a/lib/842/842_compress.c
> +++ b/lib/842/842_compress.c
> @@ -222,12 +222,13 @@ static int add_bits(struct sw842_param *p, u64 d, u8 n)
> static int add_template(struct sw842_param *p, u8 c)
> {
> int ret, i, b = 0;
> - u8 *t = comp_ops[c];
> + u8 *t = NULL;
> bool inv = false;
>
> if (c >= OPS_MAX)
> return -EINVAL;
>
> + t = comp_ops[c];
> pr_debug("template %x\n", t[4]);
>
> ret = add_bits(p, t[4], OP_BITS);
> @@ -379,12 +380,14 @@ static int add_end_template(struct sw842_param *p)
>
> static bool check_template(struct sw842_param *p, u8 c)
> {
> - u8 *t = comp_ops[c];
> + u8 *t = NULL;
> int i, match, b = 0;
>
> if (c >= OPS_MAX)
> return false;
>
> + t = comp_ops[c];
> +
> for (i = 0; i < 4; i++) {
> if (t[i] & OP_ACTION_INDEX) {
> if (t[i] & OP_AMOUNT_2)
>

thanks.
--
~Randy