linux-kernel - [PATCH] fix bad macro param in timer.c (was: kernel/timer.c: next_timer_interrupt() strange/buggy(?) code (2.6.18-rc1-mm2))

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]

Message-Id: <1153187268.9932.6.camel@localhost.localdomain>
Date:	Mon, 17 Jul 2006 21:47:48 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Andrew Morton <akpm@...l.org>, Linus Torvalds <torvalds@...l.org>
Cc:	linux-kernel@...r.kernel.org, keir@...source.com,
	Tony Lindgren <tony@...mide.com>, zach@...are.com,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andreas Mohr <andi@...x01.fht-esslingen.de>
Subject: [PATCH] fix bad macro param in timer.c  (was: kernel/timer.c:
	next_timer_interrupt() strange/buggy(?) code (2.6.18-rc1-mm2))

On Mon, 2006-07-17 at 20:53 +0200, Andreas Mohr wrote:
> Hi all,
> 
> next_timer_interrupt() contains the following gem:
> 
>         /* Check tv2-tv5. */
>         varray[0] = &base->tv2;
>         varray[1] = &base->tv3;
>         varray[2] = &base->tv4;
>         varray[3] = &base->tv5;
>         for (i = 0; i < 4; i++) {
>                 j = INDEX(i);
>                 do {
>                         if (list_empty(varray[i]->vec + j)) {
>                                 j = (j + 1) & TVN_MASK;
>                                 continue;
>                         }
>                         list_for_each_entry(nte, varray[i]->vec + j, entry)
>                                 if (time_before(nte->expires, expires))
>                                         expires = nte->expires;
>                         if (j < (INDEX(i)) && i < 3)

Looking at what INDEX is defined to be:

#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK

>                                 list = varray[i + 1]->vec + (INDEX(i + 1));

And this INDEX(i+1) is now a ... (TVR_BITS + i + 1 * TVN_BITS)) ...
This doesn't quite look like it suppose to be that way. Probably having
some funny results because of it.

Here's the patch to clean up the macro used to find the index of the
timer vector.

This is definitely a bug fix and should go into 2.6.18

-- Steve

Signed-off-by: Steven Rostedt <rostedt@...dmis.org>

Index: linux-2.6.18-rc2/kernel/timer.c
===================================================================
--- linux-2.6.18-rc2.orig/kernel/timer.c	2006-07-17 21:34:08.000000000 -0400
+++ linux-2.6.18-rc2/kernel/timer.c	2006-07-17 21:34:22.000000000 -0400
@@ -408,7 +408,7 @@ static int cascade(tvec_base_t *base, tv
  * This function cascades all vectors and executes all expired timer
  * vectors.
  */
-#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
+#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK
 
 static inline void __run_timers(tvec_base_t *base)
 {


-
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/