KMSAN: uninit-value in sd_init (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c2453450 kmsan: kcov: prettify the code unpoisoning area->..
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=17c09e53600000
kernel config: https://syzkaller.appspot.com/x/.config?x=3684f3c73f43899a
dashboard link: https://syzkaller.appspot.com/bug?extid=32310fc2aea76898d074
compiler: clang version 9.0.0 (/home/glider/llvm/clang
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f43227600000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=123bd353600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+32310f...@syzkaller.appspotmail.com

usb 1-1: New USB device found, idVendor=04f1, idProduct=1001,
bcdDevice=c3.b5
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 1-1: config 0 descriptor??
gspca_main: sunplus-2.14.0 probing 04f1:1001
gspca_sunplus: reg_w_riv err -71
=====================================================
BUG: KMSAN: uninit-value in spca504B_PollingDataReady
drivers/media/usb/gspca/sunplus.c:405 [inline]
BUG: KMSAN: uninit-value in sd_init+0x5cef/0x6060
drivers/media/usb/gspca/sunplus.c:639
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x191/0x1f0 lib/dump_stack.c:113
kmsan_report+0x14a/0x2f0 mm/kmsan/kmsan_report.c:109
__msan_warning+0x73/0xf0 mm/kmsan/kmsan_instr.c:245
spca504B_PollingDataReady drivers/media/usb/gspca/sunplus.c:405 [inline]
sd_init+0x5cef/0x6060 drivers/media/usb/gspca/sunplus.c:639
gspca_dev_probe2+0xe93/0x2230 drivers/media/usb/gspca/gspca.c:1532
gspca_dev_probe+0x346/0x3b0 drivers/media/usb/gspca/gspca.c:1605
sd_probe+0x8d/0xa0 drivers/media/usb/gspca/gl860/gl860.c:511
usb_probe_interface+0xd19/0x1310 drivers/usb/core/driver.c:361
really_probe+0xd91/0x1f90 drivers/base/dd.c:552
driver_probe_device+0x1ba/0x510 drivers/base/dd.c:721
__device_attach_driver+0x5b8/0x790 drivers/base/dd.c:828
bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:430
__device_attach+0x489/0x750 drivers/base/dd.c:894
device_initial_probe+0x4a/0x60 drivers/base/dd.c:941
bus_probe_device+0x131/0x390 drivers/base/bus.c:490
device_add+0x25b5/0x2df0 drivers/base/core.c:2201
usb_set_configuration+0x309f/0x3710 drivers/usb/core/message.c:2027
generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
usb_probe_device+0x146/0x200 drivers/usb/core/driver.c:266
really_probe+0xd91/0x1f90 drivers/base/dd.c:552
driver_probe_device+0x1ba/0x510 drivers/base/dd.c:721
__device_attach_driver+0x5b8/0x790 drivers/base/dd.c:828
bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:430
__device_attach+0x489/0x750 drivers/base/dd.c:894
device_initial_probe+0x4a/0x60 drivers/base/dd.c:941
bus_probe_device+0x131/0x390 drivers/base/bus.c:490
device_add+0x25b5/0x2df0 drivers/base/core.c:2201
usb_new_device+0x23e5/0x2fb0 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x581d/0x72f0 drivers/usb/core/hub.c:5441
process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
kthread+0x4b5/0x4f0 kernel/kthread.c:256
ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355

Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:150 [inline]
kmsan_internal_poison_shadow+0x60/0x110 mm/kmsan/kmsan.c:133
kmsan_slab_alloc+0xaa/0x130 mm/kmsan/kmsan_hooks.c:101
slab_alloc_node mm/slub.c:2792 [inline]
slab_alloc mm/slub.c:2801 [inline]
kmem_cache_alloc_trace+0x8c5/0xd20 mm/slub.c:2818
kmalloc include/linux/slab.h:556 [inline]
gspca_dev_probe2+0x30d/0x2230 drivers/media/usb/gspca/gspca.c:1464
gspca_dev_probe+0x346/0x3b0 drivers/media/usb/gspca/gspca.c:1605
sd_probe+0x8d/0xa0 drivers/media/usb/gspca/gl860/gl860.c:511
usb_probe_interface+0xd19/0x1310 drivers/usb/core/driver.c:361
really_probe+0xd91/0x1f90 drivers/base/dd.c:552
driver_probe_device+0x1ba/0x510 drivers/base/dd.c:721
__device_attach_driver+0x5b8/0x790 drivers/base/dd.c:828
bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:430
__device_attach+0x489/0x750 drivers/base/dd.c:894
device_initial_probe+0x4a/0x60 drivers/base/dd.c:941
bus_probe_device+0x131/0x390 drivers/base/bus.c:490
device_add+0x25b5/0x2df0 drivers/base/core.c:2201
usb_set_configuration+0x309f/0x3710 drivers/usb/core/message.c:2027
generic_probe+0xe7/0x280 drivers/usb/core/generic.c:210
usb_probe_device+0x146/0x200 drivers/usb/core/driver.c:266
really_probe+0xd91/0x1f90 drivers/base/dd.c:552
driver_probe_device+0x1ba/0x510 drivers/base/dd.c:721
__device_attach_driver+0x5b8/0x790 drivers/base/dd.c:828
bus_for_each_drv+0x28e/0x3b0 drivers/base/bus.c:430
__device_attach+0x489/0x750 drivers/base/dd.c:894
device_initial_probe+0x4a/0x60 drivers/base/dd.c:941
bus_probe_device+0x131/0x390 drivers/base/bus.c:490
device_add+0x25b5/0x2df0 drivers/base/core.c:2201
usb_new_device+0x23e5/0x2fb0 drivers/usb/core/hub.c:2536
hub_port_connect drivers/usb/core/hub.c:5098 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5213 [inline]
port_event drivers/usb/core/hub.c:5359 [inline]
hub_event+0x581d/0x72f0 drivers/usb/core/hub.c:5441
process_one_work+0x1572/0x1ef0 kernel/workqueue.c:2269
worker_thread+0x111b/0x2460 kernel/workqueue.c:2415
kthread+0x4b5/0x4f0 kernel/kthread.c:256
ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:355
=====================================================


---
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[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger
crash:

Reported-and-tested-by:
syzbot+32310f...@syzkaller.appspotmail.com

Tested on:

commit: e741088f stackdepot: remove code preventing compiler optim..

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

kernel config: https://syzkaller.appspot.com/x/.config?x=9e324dfe9c7b0360

dashboard link: https://syzkaller.appspot.com/bug?extid=32310fc2aea76898d074
compiler: clang version 9.0.0 (/home/glider/llvm/clang
80fee25776c2fb61e74c1ecb1a523375c2500b69)

patch: https://syzkaller.appspot.com/x/patch.diff?x=1631e564e00000

Note: testing is done by a robot and is best-effort only.