linux-kernel - [PATCH V2] lib: 842: Fix pointer dereferenced before checking

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Message-ID: <1648177073-20298-1-git-send-email-baihaowen@meizu.com>
Date:   Fri, 25 Mar 2022 10:57:53 +0800
From:   Haowen Bai <baihaowen@...zu.com>
To:     <haren@...ibm.com>
CC:     <linux-kernel@...r.kernel.org>, Haowen Bai <baihaowen@...zu.com>
Subject: [PATCH V2] lib: 842: Fix pointer dereferenced before checking

The pointer t is dereferencing comp_ops[c] before c is being
 bound checked. Fix this by assigning comp_ops[c] to t only if
c is safy, otherwise just NULL.

Signed-off-by: Haowen Bai <baihaowen@...zu.com>
---
V1->V2: fix two places that dereferenced before checking
 lib/842/842_compress.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
index c02baa4..0b47e8b 100644
--- a/lib/842/842_compress.c
+++ b/lib/842/842_compress.c
@@ -222,7 +222,7 @@ 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 = c < OPS_MAX ? comp_ops[c] : NULL;
 	bool inv = false;
 
 	if (c >= OPS_MAX)
@@ -379,7 +379,7 @@ 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 = c < OPS_MAX ? comp_ops[c] : NULL;
 	int i, match, b = 0;
 
 	if (c >= OPS_MAX)
-- 
2.7.4