From: Bart Van Assche <bvanassche@acm.org>
To: Changheun Lee <nanich.lee@samsung.com>, damien.lemoal@wdc.com
Cc: Avri.Altman@wdc.com, Johannes.Thumshirn@wdc.com,
alex_y_xu@yahoo.ca, alim.akhtar@samsung.com,
asml.silence@gmail.com, axboe@kernel.dk, bgoncalv@redhat.com,
cang@codeaurora.org, gregkh@linuxfoundation.org,
hch@infradead.org, jaegeuk@kernel.org, jejb@linux.ibm.com,
jisoo2146.oh@samsung.com, junho89.kim@samsung.com,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
ming.lei@redhat.com, mj0123.lee@samsung.com, osandov@fb.com,
patchwork-bot@kernel.org, seunghwan.hyun@samsung.com,
sookwan7.kim@samsung.com, tj@kernel.org, tom.leiming@gmail.com,
woosung2.lee@samsung.com, yi.zhang@redhat.com,
yt0928.kim@samsung.com
Subject: Re: [PATCH v12 1/3] bio: control bio max size
Date: Fri, 4 Jun 2021 07:52:35 -0700 [thread overview]
Message-ID: <63afd2d3-9fa3-9f90-a2b3-37235739f5e2@acm.org> (raw)
In-Reply-To: <20210604073459.29235-1-nanich.lee@samsung.com>
On 6/4/21 12:34 AM, Changheun Lee wrote:
>> On 2021/06/04 14:22, Changheun Lee wrote:
>>> +unsigned int bio_max_bytes(struct bio *bio)
>>> +{
>>> + struct block_device *bdev = bio->bi_bdev;
>>> +
>>> + return bdev ? bdev->bd_disk->queue->limits.max_bio_bytes : UINT_MAX;
>>> +}
>>
>> unsigned int bio_max_bytes(struct bio *bio)
>> {
>> struct block_device *bdev = bio->bi_bdev;
>>
>> if (!bdev)
>> return UINT_MAX;
>> return bdev->bd_disk->queue->limits.max_bio_bytes;
>> }
>>
>> is a lot more readable...
>> Also, I remember there was some problems with bd_disk possibly being null. Was
>> that fixed ?
>
> Thank you for review. But I'd like current style, and it's readable enough
> now I think. Null of bd_disk was just suspicion. bd_disk is not null if bdev
> is not null.
Damien is right. bd_disk can be NULL. From
https://lore.kernel.org/linux-block/20210425043020.30065-1-bvanassche@acm.org/:
"bio_max_size() may get called before device_add_disk() and hence needs to
check whether or not the block device pointer is NULL. [ ... ]
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
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"
Bart.
next prev parent reply other threads:[~2021-06-04 14:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20210604052157epcas1p2e5eebb52d08b06174696290e11fdd5a4@epcas1p2.samsung.com>
2021-06-04 5:03 ` [PATCH v12 0/3] bio: control bio max size Changheun Lee
[not found] ` <CGME20210604052159epcas1p4370bee98aad882ab335dda1565db94fb@epcas1p4.samsung.com>
2021-06-04 5:03 ` [PATCH v12 1/3] " Changheun Lee
2021-06-04 7:24 ` Damien Le Moal
[not found] ` <CGME20210604075331epcas1p13bb57f9ddfc7b112dec1ba8cf40fdc74@epcas1p1.samsung.com>
2021-06-04 7:34 ` Changheun Lee
2021-06-04 8:01 ` Damien Le Moal
[not found] ` <CGME20210604094209epcas1p26368dd18011bb2761529432cf2656a9f@epcas1p2.samsung.com>
2021-06-04 9:23 ` Changheun Lee
2021-06-04 14:52 ` Bart Van Assche [this message]
2021-06-07 6:35 ` Christoph Hellwig
2021-06-07 16:46 ` Bart Van Assche
2021-06-08 5:22 ` Christoph Hellwig
2021-06-07 6:32 ` Christoph Hellwig
[not found] ` <CGME20210607110122epcas1p4557bcbc7abac791f2557cc0d317214fd@epcas1p4.samsung.com>
2021-06-07 10:42 ` Changheun Lee
[not found] ` <CGME20210604052200epcas1p10754a3187476a0fcbfcc89c103a6d436@epcas1p1.samsung.com>
2021-06-04 5:03 ` [PATCH v12 2/3] blk-sysfs: add max_bio_bytes Changheun Lee
[not found] ` <CGME20210604052201epcas1p41a27660b20d70b7fc4295c8f131d33ce@epcas1p4.samsung.com>
2021-06-04 5:03 ` [PATCH v12 3/3] ufs: set max_bio_bytes with queue max sectors Changheun Lee
2021-06-04 16:11 ` Bart Van Assche
[not found] ` <CGME20210607094031epcas1p1f4a9ee01eaa4652ba0e8eb6a4964c952@epcas1p1.samsung.com>
2021-06-07 9:21 ` Changheun Lee
2021-06-04 6:41 ` [PATCH v12 0/3] bio: control bio max size Can Guo
2021-06-04 16:13 ` Bart Van Assche
[not found] ` <CGME20210607101609epcas1p392324f6d215e329d632a615c4b1adf4c@epcas1p3.samsung.com>
2021-06-07 9:57 ` Changheun Lee
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