[v6.1] KASAN: slab-out-of-bounds Write in try_module_get

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0182cb5b74ee Linux 6.1.162
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12c40b3a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0605c5af04d7603
dashboard link: https://syzkaller.appspot.com/bug?extid=05a4d5312254ceb6f5f6
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/91a9c745b7a1/disk-0182cb5b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a26ca15eb2ec/vmlinux-0182cb5b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/767cda5049bb/bzImage-0182cb5b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+05a4d5...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-out-of-bounds in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: slab-out-of-bounds in atomic_inc_not_zero include/linux/atomic/atomic-instrumented.h:615 [inline]
BUG: KASAN: slab-out-of-bounds in try_module_get+0x4f/0xf0 kernel/module/main.c:838
Write of size 4 at addr ffff888145765fa0 by task syz.0.568/6397

CPU: 0 PID: 6397 Comm: syz.0.568 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
print_address_description mm/kasan/report.c:316 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:420
kasan_report+0x10b/0x140 mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x235/0x290 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
atomic_inc_not_zero include/linux/atomic/atomic-instrumented.h:615 [inline]
try_module_get+0x4f/0xf0 kernel/module/main.c:838
dvb_device_open+0xf1/0x370 drivers/media/dvb-core/dvbdev.c:103
chrdev_open+0x5c5/0x6a0 fs/char_dev.c:414
do_dentry_open+0x7e9/0x10d0 fs/open.c:882
do_open fs/namei.c:3634 [inline]
path_openat+0x2635/0x2ee0 fs/namei.c:3791
do_filp_open+0x1f1/0x430 fs/namei.c:3818
do_sys_openat2+0x150/0x4b0 fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1347
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5eefd5c84e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f5ef0c9bb28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f5ef0c9c6c0 RCX: 00007f5eefd5c84e
RDX: 0000000000040002 RSI: 00007f5ef0c9bc00 RDI: ffffffffffffff9c
RBP: 00007f5ef0c9bc00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f5ef0016038 R14: 00007f5ef0015fa0 R15: 00007fffaae09a18
</TASK>

Allocated by task 1:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
____kasan_kmalloc mm/kasan/common.c:375 [inline]
__kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
dvb_register_device+0x311/0x2150 drivers/media/dvb-core/dvbdev.c:478
dvb_dmxdev_init+0x2c5/0x420 drivers/media/dvb-core/dmxdev.c:1430
vidtv_bridge_dmxdev_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:343 [inline]
vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:445 [inline]
vidtv_bridge_probe+0xb56/0xf70 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
platform_probe+0x137/0x1c0 drivers/base/platform.c:1400
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x2aa/0xc70 drivers/base/dd.c:639
__driver_probe_device+0x18c/0x330 drivers/base/dd.c:785
driver_probe_device+0x4f/0x420 drivers/base/dd.c:815
__driver_attach+0x44a/0x6e0 drivers/base/dd.c:1201
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x30a/0x5a0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:246
vidtv_bridge_init+0x39/0x67 drivers/media/test-drivers/vidtv/vidtv_bridge.c:600
do_one_initcall+0x26a/0x840 init/main.c:1310
do_initcall_level+0x137/0x1e4 init/main.c:1383
do_initcalls+0x4b/0x8a init/main.c:1399
kernel_init_freeable+0x415/0x5be init/main.c:1638
kernel_init+0x19/0x1b0 init/main.c:1526
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888145765e00
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 160 bytes to the right of
256-byte region [ffff888145765e00, ffff888145765f00)

The buggy address belongs to the physical page:
page:ffffea000515d900 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x145764
head:ffffea000515d900 order:1 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000010200 ffffea00014be400 dead000000000004 ffff888017441b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 17125260636, free_ts 0
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2559
prep_new_page mm/page_alloc.c:2566 [inline]
get_page_from_freelist+0x1a1e/0x1ab0 mm/page_alloc.c:4357
__alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5643
alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
alloc_slab_page+0x5d/0x160 mm/slub.c:1799
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x87/0x2c0 mm/slub.c:1997
___slab_alloc+0xbc6/0x1240 mm/slub.c:3154
__slab_alloc mm/slub.c:3240 [inline]
slab_alloc_node mm/slub.c:3325 [inline]
__kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
bus_add_driver+0xda/0x5a0 drivers/base/bus.c:604
driver_register+0x32d/0x430 drivers/base/driver.c:246
usb_register_driver+0x202/0x3d0 drivers/usb/core/driver.c:1062
do_one_initcall+0x26a/0x840 init/main.c:1310
do_initcall_level+0x137/0x1e4 init/main.c:1383
do_initcalls+0x4b/0x8a init/main.c:1399
kernel_init_freeable+0x415/0x5be init/main.c:1638
page_owner free stack trace missing

Memory state around the buggy address:
ffff888145765e80: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
ffff888145765f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888145765f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
^
ffff888145766000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888145766080: 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc
==================================================================


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