KASAN: out-of-bounds Read in digitv_ctrl_msg

From: Rondreis
Date: Mon Sep 19 2022 - 08:58:44 EST

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Hello,

When fuzzing the Linux kernel driver v6.0-rc4, the following crash was
triggered.

HEAD commit: 7e18e42e4b280c85b76967a9106a13ca61c16179
git tree: upstream

kernel config: https://pastebin.com/raw/xtrgsXP3
console output: https://pastebin.com/raw/cEM9u2rq

Sorry for failing to extract the reproducer. But on other versions of
Linux, I also triggered this crash.

I would appreciate it if you have any idea how to solve this bug.

The crash report is as follows:

==================================================================
BUG: KASAN: out-of-bounds in digitv_ctrl_msg+0x200/0x270
drivers/media/usb/dvb-usb/digitv.c:44
Read of size 18446744073709551615 at addr ffffc9000238fbd1 by task
syz-executor.4/8977

CPU: 0 PID: 8977 Comm: syz-executor.4 Not tainted 6.0.0-rc4+ #20
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:317 [inline]
print_report.cold+0x18a/0x66d mm/kasan/report.c:433
kasan_report+0x8a/0x1b0 mm/kasan/report.c:495
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13b/0x190 mm/kasan/generic.c:189
memcpy+0x20/0x60 mm/kasan/shadow.c:65
digitv_ctrl_msg+0x200/0x270 drivers/media/usb/dvb-usb/digitv.c:44
digitv_i2c_xfer+0x241/0x3b0 drivers/media/usb/dvb-usb/digitv.c:73
__i2c_transfer drivers/i2c/i2c-core-base.c:2109 [inline]
__i2c_transfer+0x4c2/0x16a0 drivers/i2c/i2c-core-base.c:2074
i2c_smbus_xfer_emulated+0x1be/0xf00 drivers/i2c/i2c-core-smbus.c:469
__i2c_smbus_xfer drivers/i2c/i2c-core-smbus.c:607 [inline]
__i2c_smbus_xfer+0x504/0x10b0 drivers/i2c/i2c-core-smbus.c:553
i2c_smbus_xfer drivers/i2c/i2c-core-smbus.c:545 [inline]
i2c_smbus_xfer+0x100/0x380 drivers/i2c/i2c-core-smbus.c:535
i2cdev_ioctl_smbus+0x496/0x830 drivers/i2c/i2c-dev.c:348
i2cdev_ioctl+0x3cc/0x7b0 drivers/i2c/i2c-dev.c:467
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcf784a80fd
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcf78bf8bf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcf7859c340 RCX: 00007fcf784a80fd
RDX: 00000000200003c0 RSI: 0000000000000720 RDI: 0000000000000003
RBP: 00007fcf7850b606 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffeabc59d2f R14: 00007ffeabc59ed0 R15: 00007fcf78bf8d80
</TASK>

The buggy address belongs to stack of task syz-executor.4/8977
and is located at offset 177 in frame:
i2c_smbus_xfer_emulated+0x0/0xf00 drivers/i2c/i2c-core-smbus.c:315

This frame has 3 objects:
[32, 64) 'msg'
[96, 130) 'msgbuf1'
[176, 211) 'msgbuf0'

The buggy address belongs to the virtual mapping at
[ffffc90002388000, ffffc90002391000) created by:
kernel_clone+0xe7/0x1040 kernel/fork.c:2673

The buggy address belongs to the physical page:
page:ffffea000165d400 refcount:1 mapcount:0 mapping:0000000000000000
index:0x0 pfn:0x59750
memcg:ffff88801ed70d02
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff ffff88801ed70d02
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask
0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 62, tgid 62
(kworker/u6:2), ts 245371815797, free_ts 242367217728
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook mm/page_alloc.c:2525 [inline]
prep_new_page+0x2c6/0x350 mm/page_alloc.c:2532
get_page_from_freelist+0xae9/0x3a80 mm/page_alloc.c:4283
__alloc_pages+0x321/0x710 mm/page_alloc.c:5515
alloc_pages+0x117/0x2f0 mm/mempolicy.c:2270
vm_area_alloc_pages mm/vmalloc.c:2958 [inline]
__vmalloc_area_node mm/vmalloc.c:3026 [inline]
__vmalloc_node_range+0xb2c/0x1320 mm/vmalloc.c:3196
alloc_thread_stack_node kernel/fork.c:312 [inline]
dup_task_struct kernel/fork.c:977 [inline]
copy_process+0x4608/0x6f80 kernel/fork.c:2087
kernel_clone+0xe7/0x1040 kernel/fork.c:2673
user_mode_thread+0xad/0xe0 kernel/fork.c:2742
call_usermodehelper_exec_work kernel/umh.c:174 [inline]
call_usermodehelper_exec_work+0xcc/0x180 kernel/umh.c:160
process_one_work+0x9c7/0x1650 kernel/workqueue.c:2289
worker_thread+0x623/0x1070 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1449 [inline]
free_pcp_prepare+0x5ab/0xd00 mm/page_alloc.c:1499
free_unref_page_prepare mm/page_alloc.c:3380 [inline]
free_unref_page+0x19/0x410 mm/page_alloc.c:3476
kasan_depopulate_vmalloc_pte+0x5c/0x70 mm/kasan/shadow.c:372
apply_to_pte_range mm/memory.c:2633 [inline]
apply_to_pmd_range mm/memory.c:2677 [inline]
apply_to_pud_range mm/memory.c:2713 [inline]
apply_to_p4d_range mm/memory.c:2749 [inline]
__apply_to_page_range+0x66e/0xf50 mm/memory.c:2783
kasan_release_vmalloc+0xa2/0xb0 mm/kasan/shadow.c:486
__purge_vmap_area_lazy+0x880/0x1c10 mm/vmalloc.c:1753
drain_vmap_area_work+0x52/0xe0 mm/vmalloc.c:1782
process_one_work+0x9c7/0x1650 kernel/workqueue.c:2289
worker_thread+0x623/0x1070 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

Memory state around the buggy address:
ffffc9000238fa80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc9000238fb00: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 f2 f2 f2 f2
>ffffc9000238fb80: 00 00 00 00 02 f2 f2 f2 f2 f2 00 00 00 00 03 f3
^
ffffc9000238fc00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
ffffc9000238fc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Next message: Guenter Roeck: "Re: [PATCH v5 10/21] dt-bindings: vendor-prefixes: add vendor prefix for Moortec"
Previous message: Hyeonggon Yoo: "[PATCH] mm: move PG_slab flag to page_type"
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