From: Carsten Emde <Carsten.Emde@osadl.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Ingo Molnar <mingo@elte.hu>, Li Zefan <lizf@cn.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: [PATCH] Prevent NULL pointer dereference in ftrace_raw_event_block_bio_bounce
Date: Sat, 12 Sep 2009 00:05:37 +0200 [thread overview]
Message-ID: <4AAAC9B1.9060505@osadl.org> (raw)
Booting 2.6.31 and executing
echo 1 >/sys/kernel/debug/tracing/events/enable
leads to
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<c032a583>] ftrace_raw_event_block_bio_bounce+0x4b/0xb9
Apparently,
bio = bio_map_user(q, NULL, uaddr, len, reading, gfp_mask);
is called in block/blk-map.c:58 where bio->bi_bdev in set to NULL and
still is NULL when an attempt is made to evaluate bio->bi_bdev->bd_dev
in include/trace/events/block.h:189.
The tracepoint should ensure bio->bi_bdev is not dereferenced, if NULL.
Signed-Off-By: Carsten Emde <C.Emde@osadl.org>
--- a/include/trace/events/block.h 2009-09-11 21:20:56.000000000 +0200
+++ b/include/trace/events/block.h 2009-09-11 22:01:52.000000000 +0200
@@ -186,7 +186,8 @@
),
TP_fast_assign(
- __entry->dev = bio->bi_bdev->bd_dev;
+ __entry->dev = bio->bi_bdev ?
+ bio->bi_bdev->bd_dev : 0;
__entry->sector = bio->bi_sector;
__entry->nr_sector = bio->bi_size >> 9;
blk_fill_rwbs(__entry->rwbs, bio->bi_rw, bio->bi_size);
next reply other threads:[~2009-09-11 22:35 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-11 22:05 Carsten Emde [this message]
2009-09-11 22:15 ` [PATCH] Prevent NULL pointer dereference in ftrace_raw_event_block_bio_bounce Steven Rostedt
2009-09-13 15:01 ` [tip:tracing/core] tracing: prevent " tip-bot for Carsten Emde
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