linux-kernel - [PATCH 3/5] printk: Add comment about tricky check for text buffer size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 14 Feb 2014 17:47:34 +0100
From:	Petr Mladek <pmladek@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jan Kara <jack@...e.cz>, Michal Hocko <mhocko@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>,
	Petr Mladek <pmladek@...e.cz>
Subject: [PATCH 3/5] 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@...e.cz>
---
 kernel/printk/printk.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 54a4439d021c..bc6eed48a454 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1562,6 +1562,11 @@ 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;
 		}
-- 
1.8.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/