| Message ID | 20221011142253.4015966-1-yukuai1@huaweicloud.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] blk-mq: fix null pointer dereference in blk_mq_clear_rq_mapping() | expand |
Hi, Jens! 在 2022/10/11 22:22, Yu Kuai 写道: > From: Yu Kuai <yukuai3@huawei.com> > > Our syzkaller report a null pointer dereference, root cause is > following: > > __blk_mq_alloc_map_and_rqs > set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs > blk_mq_alloc_map_and_rqs > blk_mq_alloc_rqs > // failed due to oom > alloc_pages_node > // set->tags[hctx_idx] is still NULL > blk_mq_free_rqs > drv_tags = set->tags[hctx_idx]; > // null pointer dereference is triggered > blk_mq_clear_rq_mapping(drv_tags, ...) > > This is because commit 63064be150e4 ("blk-mq: > Add blk_mq_alloc_map_and_rqs()") merged the two steps: > > 1) set->tags[hctx_idx] = blk_mq_alloc_rq_map() > 2) blk_mq_alloc_rqs(..., set->tags[hctx_idx]) > > into one step: > > set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs() > > Since tags is not initialized yet in this case, fix the problem by > checking if tags is NULL pointer in blk_mq_clear_rq_mapping(). > > Fixes: 63064be150e4 ("blk-mq: Add blk_mq_alloc_map_and_rqs()") > Signed-off-by: Yu Kuai <yukuai3@huawei.com> > Reviewed-by: John Garry <john.garry@huawei.com> > --- > Changes in v2: > - fix spelling mistakes > - add review tag > > block/blk-mq.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > Can you apply this patch? Thanks, Kuai > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 8070b6c10e8d..33292c01875d 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -3112,8 +3112,11 @@ static void blk_mq_clear_rq_mapping(struct blk_mq_tags *drv_tags, > struct page *page; > unsigned long flags; > > - /* There is no need to clear a driver tags own mapping */ > - if (drv_tags == tags) > + /* > + * There is no need to clear mapping if driver tags is not initialized > + * or the mapping belongs to the driver tags. > + */ > + if (!drv_tags || drv_tags == tags) > return; > > list_for_each_entry(page, &tags->page_list, lru) { >
On Tue, 11 Oct 2022 22:22:53 +0800, Yu Kuai wrote: > From: Yu Kuai <yukuai3@huawei.com> > > Our syzkaller report a null pointer dereference, root cause is > following: > > __blk_mq_alloc_map_and_rqs > set->tags[hctx_idx] = blk_mq_alloc_map_and_rqs > blk_mq_alloc_map_and_rqs > blk_mq_alloc_rqs > // failed due to oom > alloc_pages_node > // set->tags[hctx_idx] is still NULL > blk_mq_free_rqs > drv_tags = set->tags[hctx_idx]; > // null pointer dereference is triggered > blk_mq_clear_rq_mapping(drv_tags, ...) > > [...] Applied, thanks! [1/1] blk-mq: fix null pointer dereference in blk_mq_clear_rq_mapping() commit: 76dd298094f484c6250ebd076fa53287477b2328 Best regards,
diff --git a/block/blk-mq.c b/block/blk-mq.c index 8070b6c10e8d..33292c01875d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3112,8 +3112,11 @@ static void blk_mq_clear_rq_mapping(struct blk_mq_tags *drv_tags, struct page *page; unsigned long flags; - /* There is no need to clear a driver tags own mapping */ - if (drv_tags == tags) + /* + * There is no need to clear mapping if driver tags is not initialized + * or the mapping belongs to the driver tags. + */ + if (!drv_tags || drv_tags == tags) return; list_for_each_entry(page, &tags->page_list, lru) {