This is a note to let you know that I've just added the patch titled
printk: Fix calculation of length used to discard records
to the 3.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
printk-fix-calculation-of-length-used-to-discard-records.patch
and it can be found in the queue-3.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From e3756477aec028427fec767957c0d4b6cfb87208 Mon Sep 17 00:00:00 2001
From: Jeff Mahoney <je...@suse.com>
Date: Fri, 10 Aug 2012 15:07:09 -0400
Subject: printk: Fix calculation of length used to discard records
From: Jeff Mahoney <je...@suse.com>
commit e3756477aec028427fec767957c0d4b6cfb87208 upstream.
While tracking down a weird buffer overflow issue in a program that
looked to be sane, I started double checking the length returned by
syslog(SYSLOG_ACTION_READ_ALL, ...) to make sure it wasn't overflowing
the buffer.
Sure enough, it was. I saw this in strace:
11339 syslog(SYSLOG_ACTION_READ_ALL, "<5>[244017.708129] REISERFS (dev"...,
8192) = 8279
It turns out that the loops that calculate how much space the entries
will take when they're copied don't include the newlines and prefixes
that will be included in the final output since prev flags is passed as
zero.
This patch properly accounts for it and fixes the overflow.
Signed-off-by: Jeff Mahoney <je...@suse.com>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
kernel/printk.c | 2 ++
1 file changed, 2 insertions(+)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -999,6 +999,7 @@ static int syslog_print_all(char __user
struct log *msg = log_from_idx(idx);
len += msg_print_text(msg, prev, true, NULL, 0);
+ prev = msg->flags;
idx = log_next(idx);
seq++;
}
@@ -1011,6 +1012,7 @@ static int syslog_print_all(char __user
struct log *msg = log_from_idx(idx);
len -= msg_print_text(msg, prev, true, NULL, 0);
+ prev = msg->flags;
idx = log_next(idx);
seq++;
}
Patches currently in stable-queue which might be from je...@suse.com are
queue-3.5/printk-fix-calculation-of-length-used-to-discard-records.patch
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