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From: David Howells <dhowells@redhat.com>
To: Zijun Hu <zijun_hu@icloud.com>
Cc: dhowells@redhat.com, Alexander Viro <viro@zeniv.linux.org.uk>,
	Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Zijun Hu <quic_zijuhu@quicinc.com>
Subject: Re: [PATCH 1/5] fs/filesystems: Fix potential unsigned integer underflow in fs_name()
Date: Fri, 11 Apr 2025 16:34:05 +0100	[thread overview]
Message-ID: <2425260.1744385645@warthog.procyon.org.uk> (raw)
In-Reply-To: <20250410-fix_fs-v1-1-7c14ccc8ebaa@quicinc.com>

Zijun Hu <zijun_hu@icloud.com> wrote:

> fs_name() has @index as unsigned int, so there is underflow risk for
> operation '@index--'.
> 
> Fix by breaking the for loop when '@index == 0' which is also more proper
> than '@index <= 0' for unsigned integer comparison.

There isn't really a risk.  The list walked by "tmp" and the checks that this
is or is not NULL will prevent a problem.

I also feel that breaking out of the loop with "<= 0" - even if the variable
is unsigned - is safer, on the off chance that someone in the future changes
the signedness of the variable.

David


  parent reply	other threads:[~2025-04-11 15:34 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-10 11:45 [PATCH 0/5] fs: bug fixes Zijun Hu
2025-04-10 11:45 ` [PATCH 1/5] fs/filesystems: Fix potential unsigned integer underflow in fs_name() Zijun Hu
2025-04-11 14:34   ` (subset) " Christian Brauner
2025-04-11 14:35   ` Christian Brauner
2025-04-11 14:52     ` Zijun Hu
2025-04-11 15:34   ` David Howells [this message]
2025-04-11 16:06     ` Zijun Hu
2025-04-10 11:45 ` [PATCH 2/5] fs/fs_parse: Fix macro fsparam_u32hex() definition Zijun Hu
2025-04-11 14:17   ` Christian Brauner
2025-04-11 14:25     ` Zijun Hu
2025-04-10 11:45 ` [PATCH 3/5] fs/fs_parse: Fix 3 issues for validate_constant_table() Zijun Hu
2025-04-11 14:37   ` Christian Brauner
2025-04-11 14:48     ` Zijun Hu
2025-04-14 12:39       ` Jan Kara
2025-04-10 11:45 ` [PATCH 4/5] fs/fs_parse: Correct comments of fs_validate_description() Zijun Hu
2025-04-11 14:20   ` (subset) " Christian Brauner
2025-04-10 11:45 ` [PATCH 5/5] fs/fs_context: Mark an unlikely if condition with unlikely() in vfs_parse_monolithic_sep() Zijun Hu
2025-04-11 14:24   ` (subset) " Christian Brauner

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