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From: Nathan Chancellor <natechancellor@gmail.com>
To: Petr Mladek <pmladek@suse.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: -Wfortify-source in kernel/printk/printk.c
Date: Wed, 29 Jan 2020 19:16:48 -0700	[thread overview]
Message-ID: <20200130021648.GA32309@ubuntu-x2-xlarge-x86> (raw)

Hi all,

After commit 6d485ff455e ("Improve static checks for sprintf and
__builtin___sprintf_chk") in clang [1], the following warning appears
when CONFIG_PRINTK is disabled (e.g. allnoconfig):

../kernel/printk/printk.c:2416:10: warning: 'sprintf' will always
overflow; destination buffer has size 0, but format string expands
to at least 33 [-Wfortify-source]
                        len = sprintf(text,
                              ^
1 warning generated.

Specifically referring to
https://elixir.bootlin.com/linux/v5.5/source/kernel/printk/printk.c#L2416.

It isn't wrong, given that when CONFIG_PRINTK is disabled, text's length
is 0 (LOG_LINE_MAX and PREFIX_MAX are both zero). How should this
warning be dealt this? I am not familiar enough with the printk code to
say myself.

[1]: https://github.com/llvm/llvm-project/commit/6d485ff455ea2b37fef9e06e426dae6c1241b231

Cheers,
Nathan

             reply	other threads:[~2020-01-30  2:16 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-30  2:16 Nathan Chancellor [this message]
2020-01-30  5:17 ` -Wfortify-source in kernel/printk/printk.c Sergey Senozhatsky
2020-01-30  6:39   ` Joe Perches
2020-01-30  6:57     ` Sergey Senozhatsky

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