From e8c42d36ab86cf45f88c3a0e344233b1032fbf3d Mon Sep 17 00:00:00 2001 From: Petr Mladek <pmladek@suse.cz> Date: Thu, 3 Apr 2014 14:48:41 -0700 Subject: [PATCH] printk: add comment about tricky check for text buffer size There is no check for potential "text_len" overflow. It is not needed because only valid level is detected. It took me some time to understand why. It would deserve a comment ;-) Signed-off-by: Petr Mladek <pmladek@suse.cz> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Kay Sievers <kay@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- kernel/printk/printk.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index db7a02e05241..012f3e40671d 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1561,6 +1561,11 @@ asmlinkage int vprintk_emit(int facility, int level, case 'd': /* KERN_DEFAULT */ lflags |= LOG_PREFIX; } + /* + * No need to check length here because vscnprintf + * put '\0' at the end of the string. Only valid and + * newly printed level is detected. + */ text_len -= end_of_header - text; text = (char *)end_of_header; } -- GitLab