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From: Aurelien Jarno <aurelien@aurel32.net>
To: gao.rui@zte.com.cn
Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr, jiangfeng@kylinos.cn,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: lib: Fix address overflow due to large count values in strnlen ZBB path
Date: Sat, 22 Aug 2026 11:53:15 +0200	[thread overview]
Message-ID: <aolxiwRzSDlJt2t5@aurel32.net> (raw)
In-Reply-To: <20260819161821053fNUWuvdGIo4HUBmxlcNfG@zte.com.cn>

Hi,

On 2026-08-19 16:18, gao.rui@zte.com.cn wrote:
> Hi all,
> 
> This patch fixes an issue in the RISC-V ZBB optimized strnlen implementation.
> 
> Problem description: When using the ZBB optimized strnlen implementation, passing very large count values (such as SIZE_MAX) can cause address overflow and return incorrect results.
> 
> This issue was observed in device-mapper tests:
> 
> sh-5.2# dmsetup create testname9 --table "0 8 zero"
> sh-5.2# cat /sys/block/dm-*/dm/name
> testname
> sh-5.2# dmsetup remove testname9
> 
> The overflow in strnlen caused failures in string handling during device-mapper operations.
> 
> Patch summary:
> - Explicitly introduce the strnlen_generic label.
> - Simplify the generic implementation loop.

This part should be in a separate patch, separated from the bug fix, and 
if possible with some benchmark.

> - Add fallback logic in strnlen_zbb to redirect to the generic path when a0 + a1 overflows.
> This ensures correct behavior for large count values and SIZE_MAX cases.

Is there a way to instead to fix the strnlen_zbb to avoid the fallback?

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

WARNING: multiple messages have this Message-ID (diff)
From: Aurelien Jarno <aurelien@aurel32.net>
To: gao.rui@zte.com.cn
Cc: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr, jiangfeng@kylinos.cn,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] riscv: lib: Fix address overflow due to large count values in strnlen ZBB path
Date: Sat, 22 Aug 2026 11:53:15 +0200	[thread overview]
Message-ID: <aolxiwRzSDlJt2t5@aurel32.net> (raw)
In-Reply-To: <20260819161821053fNUWuvdGIo4HUBmxlcNfG@zte.com.cn>

Hi,

On 2026-08-19 16:18, gao.rui@zte.com.cn wrote:
> Hi all,
> 
> This patch fixes an issue in the RISC-V ZBB optimized strnlen implementation.
> 
> Problem description: When using the ZBB optimized strnlen implementation, passing very large count values (such as SIZE_MAX) can cause address overflow and return incorrect results.
> 
> This issue was observed in device-mapper tests:
> 
> sh-5.2# dmsetup create testname9 --table "0 8 zero"
> sh-5.2# cat /sys/block/dm-*/dm/name
> testname
> sh-5.2# dmsetup remove testname9
> 
> The overflow in strnlen caused failures in string handling during device-mapper operations.
> 
> Patch summary:
> - Explicitly introduce the strnlen_generic label.
> - Simplify the generic implementation loop.

This part should be in a separate patch, separated from the bug fix, and 
if possible with some benchmark.

> - Add fallback logic in strnlen_zbb to redirect to the generic path when a0 + a1 overflows.
> This ensures correct behavior for large count values and SIZE_MAX cases.

Is there a way to instead to fix the strnlen_zbb to avoid the fallback?

Regards
Aurelien

-- 
Aurelien Jarno                          GPG: 4096R/1DDD8C9B
aurelien@aurel32.net                     http://aurel32.net

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  reply	other threads:[~2026-08-22  9:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-19  8:18 [PATCH] riscv: lib: Fix address overflow due to large count values in strnlen ZBB path gao.rui
2026-08-19  8:18 ` gao.rui
2026-08-22  9:53 ` Aurelien Jarno [this message]
2026-08-22  9:53   ` Aurelien Jarno
2026-08-24  8:12   ` gao.rui
2026-09-23 20:03     ` Jason Montleon
  -- strict thread matches above, loose matches on Subject: below --
2026-08-24  8:20 gao.rui
2026-08-24  8:20 ` gao.rui

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