KMSAN: uninit-value in ld_usb_read (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=12d6dc5f600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3684f3c73f43899a
dashboard link: https://syzkaller.appspot.com/bug?extid=fd49690bb45caaacf578
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=157c63d7600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1180adab600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+fd49690bb45caaacf578@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in ld_usb_read+0x870/0xc50  
drivers/usb/misc/ldusb.c:487
CPU: 1 PID: 12745 Comm: syz-executor511 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
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
 ld_usb_read+0x870/0xc50 drivers/usb/misc/ldusb.c:487
 __vfs_read+0x1a9/0xc90 fs/read_write.c:425
 vfs_read+0x359/0x6f0 fs/read_write.c:461
 ksys_read+0x265/0x430 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:595
 __x64_sys_read+0x4a/0x70 fs/read_write.c:595
 do_syscall_64+0xb6/0x160 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x4418a9
Code: e8 8c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd63549848 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004418a9
RDX: 0000000000000002 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00000000006cc018 R08: 000000000000000f R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402600
R13: 0000000000402690 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags+0x3f/0x90 mm/kmsan/kmsan.c:150
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:364 [inline]
 kmsan_alloc_page+0x153/0x370 mm/kmsan/kmsan_shadow.c:393
 __alloc_pages_nodemask+0x149d/0x60c0 mm/page_alloc.c:4794
 alloc_pages_current+0x68d/0x9a0 mm/mempolicy.c:2188
 alloc_pages include/linux/gfp.h:511 [inline]
 kmalloc_order mm/slab_common.c:1303 [inline]
 kmalloc_order_trace+0x94/0x3f0 mm/slab_common.c:1319
 kmalloc_large include/linux/slab.h:485 [inline]
 __kmalloc+0x2e6/0x430 mm/slub.c:3825
 kmalloc_array+0x86/0x110 include/linux/slab.h:618
 ld_usb_probe+0x64f/0x1460 drivers/usb/misc/ldusb.c:697
 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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