From: Petr Mladek Date: Tue, 17 Jan 2023 16:10:31 +0000 (+0100) Subject: printk: Use scnprintf() to print the message about the dropped messages on a console X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=d551afc25878924991a4c65299dfa83df1cb9ef8;p=linux.git printk: Use scnprintf() to print the message about the dropped messages on a console Use scnprintf() for printing the message about dropped messages on a console. It returns the really written length of the message. It prevents potential buffer overflow when the returned length is later used to copy the buffer content. Note that the previous code was safe because the scratch buffer was big enough and the message always fit in. But scnprintf() makes it more safe, definitely. Reported-by: coverity-bot Addresses-Coverity-ID: 1530570 ("Memory - corruptions") Fixes: c4fcc617e148 ("printk: introduce console_prepend_dropped() for dropped messages") Link: https://lore.kernel.org/r/202301131544.D9E804CCD@keescook Reviewed-by: John Ogness Reviewed-by: Sergey Senozhatsky Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20230117161031.15499-1-pmladek@suse.com --- diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 55338bfd3b553..a9b7dade0d2ec 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2716,7 +2716,7 @@ static void console_prepend_dropped(struct printk_message *pmsg, unsigned long d char *outbuf = &pbufs->outbuf[0]; size_t len; - len = snprintf(scratchbuf, scratchbuf_sz, + len = scnprintf(scratchbuf, scratchbuf_sz, "** %lu printk messages dropped **\n", dropped); /*