From: Dan Carpenter <dan.carpenter@linaro.org>
To: Zhongkun He <hezhongkun.hzk@bytedance.com>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, mhocko@suse.com,
yosry.ahmed@linux.dev, muchun.song@linux.dev, yuzhao@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V3 2/3] mm: add max swappiness arg to lru_gen for anonymous memory only
Date: Wed, 30 Apr 2025 10:59:11 +0300 [thread overview]
Message-ID: <aBHYT27M1tRxNLRj@stanley.mountain> (raw)
In-Reply-To: <b3af3747daefa00177b48f4666780da58177f7c0.1744169302.git.hezhongkun.hzk@bytedance.com>
On Wed, Apr 09, 2025 at 03:06:19PM +0800, Zhongkun He wrote:
> + /* set by userspace for anonymous memory only */
> + if (!strncmp("max", swap_string, sizeof("max"))) {
This pattern of strncmp("foo", str, sizeof("foo")) is exactly the same
as strcmp(). It doesn't provide any additional security. The strncmp()
function is meant for matching string prefixes and it's a relatively
common bug to do this:
intended: if (strcmp(string, "prefix", sizeof("prefix") - 1) == 0) {
actual: if (strcmp(string, "prefix", sizeof("prefix")) == 0) {
I have a static checker warning for these:
https://lore.kernel.org/all/30210ed77b40b4b6629de659cb56b9ec7832c447.1744452787.git.dan.carpenter@linaro.org/
If people deliberately misuse the function then it makes it trickier
to tell accidental mistakes from deliberate mistakes.
regards,
dan carpenter
next prev parent reply other threads:[~2025-04-30 7:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-09 7:06 [PATCH V3 0/3] add max arg to swappiness in memory.reclaim and lru_gen Zhongkun He
2025-04-09 7:06 ` [PATCH V3 1/3] mm: add swappiness=max arg to memory.reclaim for only anon reclaim Zhongkun He
2025-04-10 2:09 ` Andrew Morton
2025-04-10 3:48 ` [External] " Zhongkun He
2025-04-09 7:06 ` [PATCH V3 2/3] mm: add max swappiness arg to lru_gen for anonymous memory only Zhongkun He
2025-04-10 2:09 ` Andrew Morton
2025-04-10 4:50 ` [External] " Zhongkun He
2025-04-30 7:59 ` Dan Carpenter [this message]
2025-05-01 1:56 ` Zhongkun He
2025-05-02 6:58 ` Dan Carpenter
2025-05-07 3:27 ` Zhongkun He
2025-04-09 7:06 ` [PATCH V3 3/3] mm: vmscan: add more comments about cache_trim_mode Zhongkun He
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