linux-kernel - [PATCH] zram: correctly handle all next

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Message-Id: <20230103030119.1496358-1-senozhatsky@chromium.org>
Date:   Tue,  3 Jan 2023 12:01:19 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH] zram: correctly handle all next_arg() cases

When supplied buffer does not have assignment sign
next_arg() sets `val` pointer to NULL, so we cannot
dereference it. Add a NULL pointer test to handle
`param` case, in addition to `*val` test, which
handles cases when param has no value assigned to
it: `param=`.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 drivers/block/zram/zram_drv.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e290d6d97047..70c412eb6c1f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1140,7 +1140,7 @@ static ssize_t recomp_algorithm_store(struct device *dev,
 	while (*args) {
 		args = next_arg(args, &param, &val);
 
-		if (!*val)
+		if (!val || !*val)
 			return -EINVAL;
 
 		if (!strcmp(param, "algo")) {
@@ -1824,7 +1824,7 @@ static ssize_t recompress_store(struct device *dev,
 	while (*args) {
 		args = next_arg(args, &param, &val);
 
-		if (!*val)
+		if (!val || !*val)
 			return -EINVAL;
 
 		if (!strcmp(param, "type")) {
-- 
2.39.0.314.g84b9a713c41-goog