2020-07-27 06:53:19

by Huang Guobin

Subject: [PATCH v2] 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 | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
index c02baa4168e1..c37bfe0b9346 100644
--- a/lib/842/842_compress.c
+++ b/lib/842/842_compress.c
@@ -11,6 +11,7 @@
#define MODULE_NAME "842_compress"

#include <linux/hashtable.h>
+#include <linux/nospec.h>

#include "842.h"
#include "842_debugfs.h"
@@ -222,12 +223,14 @@ 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;
+ c = array_index_nospec(c, OPS_MAX);

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

ret = add_bits(p, t[4], OP_BITS);
@@ -379,12 +382,14 @@ 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;
+ c = array_index_nospec(c, OPS_MAX);

+ 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

2020-07-27 06:55:37

by Herbert Xu

Subject: Re: [PATCH v2] lib: Verify array index is correct before using it

On Mon, Jul 27, 2020 at 02:59:10AM -0400, 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]>
> ---
> lib/842/842_compress.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)

Please post this to [email protected].

Thanks,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt