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,
Nathan Chancellor <natechancellor@gmail.com>
Subject: [PATCH] printk: Convert a use of sprintf to snprintf in console_unlock
Date: Thu, 30 Jan 2020 15:16:44 -0700 [thread overview]
Message-ID: <20200130221644.2273-1-natechancellor@gmail.com> (raw)
When CONFIG_PRINTK is disabled (e.g. when building allnoconfig), clang
warns:
../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.
It is not wrong; text has a zero size when CONFIG_PRINTK is disabled
because LOG_LINE_MAX and PREFIX_MAX are both zero. Change to snprintf so
that this case is explicitly handled without any risk of overflow.
Link: https://github.com/ClangBuiltLinux/linux/issues/846
Link: https://github.com/llvm/llvm-project/commit/6d485ff455ea2b37fef9e06e426dae6c1241b231
Link: https://lore.kernel.org/lkml/20200130051711.GF115889@google.com/
Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
kernel/printk/printk.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index fada22dc4ab6..a44094727a5c 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2413,9 +2413,9 @@ void console_unlock(void)
printk_safe_enter_irqsave(flags);
raw_spin_lock(&logbuf_lock);
if (console_seq < log_first_seq) {
- len = sprintf(text,
- "** %llu printk messages dropped **\n",
- log_first_seq - console_seq);
+ len = snprintf(text, sizeof(text),
+ "** %llu printk messages dropped **\n",
+ log_first_seq - console_seq);
/* messages are gone, move to first one */
console_seq = log_first_seq;
--
2.25.0
next reply other threads:[~2020-01-30 22:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 22:16 Nathan Chancellor [this message]
2020-01-31 7:02 ` [PATCH] printk: Convert a use of sprintf to snprintf in console_unlock Sergey Senozhatsky
2020-02-11 13:05 ` Petr Mladek
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