Messages in this thread | | | Subject | Re: [PATCH] Prevent NULL pointer dereference in ftrace_raw_event_block_bio_bounce | From | Steven Rostedt <> | Date | Fri, 11 Sep 2009 18:15:04 -0400 |
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On Sat, 2009-09-12 at 00:05 +0200, Carsten Emde wrote: > 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>
Thanks Carsten!
I'll apply it and push it off to Ingo.
-- Steve
> > --- 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); >
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