The SCSI core sends the REPORT LUNS and INQUIRY commands before calling
device_add_disk(). This patch prevents that bio_max_size() triggers the
following kernel crash during a SCSI LUN scan:
BUG: KASAN: null-ptr-deref in bio_add_hw_page+0xa6/0x310
Read of size 8 at addr 00000000000005a8 by task kworker/u16:0/7
CPU: 0 PID: 7 Comm: kworker/u16:0 Not tainted 5.12.0-rc8-dbg+ #18
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
Workqueue: events_unbound async_run_entry_fn
Call Trace:
show_stack+0x52/0x58
dump_stack+0x9d/0xcf
kasan_report.cold+0x4b/0x50
__asan_load8+0x69/0x90
bio_add_hw_page+0xa6/0x310
bio_add_pc_page+0xaa/0xe0
bio_map_kern+0xdc/0x1a0
blk_rq_map_kern+0xcd/0x2d0
__scsi_execute+0x9a/0x290 [scsi_mod]
scsi_probe_lun.constprop.0+0x17c/0x660 [scsi_mod]
scsi_probe_and_add_lun+0x178/0x750 [scsi_mod]
__scsi_add_device+0x18c/0x1a0 [scsi_mod]
ata_scsi_scan_host+0xe5/0x260 [libata]
async_port_probe+0x94/0xb0 [libata]
async_run_entry_fn+0x7d/0x2d0
process_one_work+0x582/0xac0
worker_thread+0x8f/0x5a0
kthread+0x222/0x250
ret_from_fork+0x1f/0x30
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Changheun Lee <nanich.lee@xxxxxxxxxxx>
Cc: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Fixes: 15050b63567c ("bio: limit bio max size")
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
block/bio.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index d718c63b3533..a8879ee6c59a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -257,9 +257,10 @@ EXPORT_SYMBOL(bio_init);
unsigned int bio_max_size(struct bio *bio)
{
- struct request_queue *q = bio->bi_bdev->bd_disk->queue;
+ if (!bio->bi_bdev)
+ return UINT_MAX;
- return q->limits.bio_max_bytes;
+ return bio->bi_bdev->bd_disk->queue->limits.bio_max_bytes;
}
/**
