KMSAN: uninit-value in scsi_mode_sense

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ce8056d1 wip: changed copy_from_user where instrumented
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=10278e91900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f
dashboard link: https://syzkaller.appspot.com/bug?extid=6b02c1da3865f750164a
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=177d957a900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14528186900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6b02c1...@syzkaller.appspotmail.com

sd 1:0:0:0: [sdb] 0 512-byte logical blocks: (0 B/0 B)
sd 1:0:0:0: [sdb] 0-byte physical blocks
=====================================================
BUG: KMSAN: uninit-value in scsi_mode_sense+0x10f0/0x17b0 drivers/scsi/scsi_lib.c:2138
CPU: 1 PID: 624 Comm: kworker/u4:6 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound async_run_entry_fn
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x21c/0x280 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
scsi_mode_sense+0x10f0/0x17b0 drivers/scsi/scsi_lib.c:2138
sd_read_write_protect_flag drivers/scsi/sd.c:2636 [inline]
sd_revalidate_disk+0x4ffa/0xdae0 drivers/scsi/sd.c:3175
sd_probe+0x10d1/0x18c0 drivers/scsi/sd.c:3405
really_probe+0xf20/0x20b0 drivers/base/dd.c:529
driver_probe_device+0x293/0x390 drivers/base/dd.c:701
__device_attach_driver+0x63f/0x830 drivers/base/dd.c:807
bus_for_each_drv+0x2ca/0x3f0 drivers/base/bus.c:431
__device_attach_async_helper+0x31a/0x3f0 drivers/base/dd.c:833
async_run_entry_fn+0x1a2/0x7d0 kernel/async.c:123
process_one_work+0x1688/0x2140 kernel/workqueue.c:2269
worker_thread+0x10bc/0x2730 kernel/workqueue.c:2415
kthread+0x551/0x590 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310
kmsan_memcpy_memmove_metadata+0x272/0x2e0 mm/kmsan/kmsan.c:247
kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267
__msan_memcpy+0x43/0x50 mm/kmsan/kmsan_instr.c:116
bio_copy_kern_endio_read+0x494/0x5f0 block/blk-map.c:448
bio_endio+0xce1/0xde0 block/bio.c:1447
req_bio_endio block/blk-core.c:261 [inline]
blk_update_request+0x1178/0x2710 block/blk-core.c:1569
scsi_end_request+0x102/0xc00 drivers/scsi/scsi_lib.c:558
scsi_io_completion+0x34f/0x2f20 drivers/scsi/scsi_lib.c:934
scsi_finish_command+0x85b/0x880 drivers/scsi/scsi.c:214
scsi_softirq_done+0x683/0xa80 drivers/scsi/scsi_lib.c:1460
blk_done_softirq+0x2fe/0x4e0 block/blk-softirq.c:37
__do_softirq+0x2ea/0x7f5 kernel/softirq.c:293

Uninit was created at:
kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:293
__alloc_pages_nodemask+0xdf0/0x1030 mm/page_alloc.c:4889
alloc_pages_current+0x685/0xb50 mm/mempolicy.c:2292
alloc_pages include/linux/gfp.h:545 [inline]
bio_copy_kern block/blk-map.c:494 [inline]
blk_rq_map_kern+0xdda/0x1570 block/blk-map.c:743
__scsi_execute+0x318/0xc80 drivers/scsi/scsi_lib.c:258
scsi_execute_req include/scsi/scsi_device.h:460 [inline]
scsi_mode_sense+0x600/0x17b0 drivers/scsi/scsi_lib.c:2115
sd_read_write_protect_flag drivers/scsi/sd.c:2636 [inline]
sd_revalidate_disk+0x4ffa/0xdae0 drivers/scsi/sd.c:3175
sd_probe+0x10d1/0x18c0 drivers/scsi/sd.c:3405
really_probe+0xf20/0x20b0 drivers/base/dd.c:529
driver_probe_device+0x293/0x390 drivers/base/dd.c:701
__device_attach_driver+0x63f/0x830 drivers/base/dd.c:807
bus_for_each_drv+0x2ca/0x3f0 drivers/base/bus.c:431
__device_attach_async_helper+0x31a/0x3f0 drivers/base/dd.c:833
async_run_entry_fn+0x1a2/0x7d0 kernel/async.c:123
process_one_work+0x1688/0x2140 kernel/workqueue.c:2269
worker_thread+0x10bc/0x2730 kernel/workqueue.c:2415
kthread+0x551/0x590 kernel/kthread.c:292
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293
=====================================================


---
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syzbot can test patches for this issue, for details see:
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[syzbot]

> #syz test: upstream

want 2 args (repo, branch), got 1

>

[syzbot]

> #syz test: upstream master

"upstream" does not look like a valid git repo address.

>

[syzbot]

> #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree
because KMSAN tool is not upstreamed yet.
See https://goo.gl/tpsmEJ#kmsan-bugs for details.

>

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in scsi_mode_sense

=====================================================
BUG: KMSAN: uninit-value in scsi_mode_sense+0x10f0/0x17b0 drivers/scsi/scsi_lib.c:2138

CPU: 1 PID: 365 Comm: kworker/u4:6 Not tainted 5.8.0-rc5-syzkaller #0

Tested on:

commit: 3b3ea602 x86: add failure injection to get/put/clear_user

git tree: https://github.com/google/kmsan.git master

console output: https://syzkaller.appspot.com/x/log.txt?x=160580cd900000

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.