From: Nathan Chancellor Date: Thu, 30 Jan 2020 22:16:44 +0000 (-0700) Subject: printk: Convert a use of sprintf to snprintf in console_unlock X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=5661dd95a2958634485bb1a53f90a6ab621d4b0c;p=linux.git printk: Convert a use of sprintf to snprintf in console_unlock 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: http://lkml.kernel.org/r/20200130221644.2273-1-natechancellor@gmail.com Cc: Steven Rostedt Cc: linux-kernel@vger.kernel.org Cc: clang-built-linux@googlegroups.com Signed-off-by: Nathan Chancellor Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek --- diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fada22dc4ab6c..a44094727a5c8 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2413,9 +2413,9 @@ again: 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;