Messages in this thread Patch in this message | | | Date | Sat, 12 Sep 2009 00:05:37 +0200 | From | Carsten Emde <> | Subject | [PATCH] Prevent NULL pointer dereference in ftrace_raw_event_block_bio_bounce |
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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);
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