syzbot


KASAN: use-after-free Read in load_firmware_cb (2)

Status: upstream: reported C repro on 2025/10/18 16:24
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+f7a358f1f862868c8937@syzkaller.appspotmail.com
First crash: 147d, last: 30d
Fix bisection: failed (error log)
  
Bug presence (2)
Date Name Commit Repro Result
2025/10/20 upstream (ToT) d9043c79ba68 C [report] KASAN: slab-use-after-free Read in load_firmware_cb
2026/03/03 upstream (ToT) af4e9ef3d784 C Failed due to an error; will retry later
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in load_firmware_cb usb media 19 C 12 1291d 2207d 0/29 auto-obsoleted due to no activity on 2023/11/09 13:12
linux-6.1 KASAN: use-after-free Read in load_firmware_cb 19 2 589d 590d 0/3 auto-obsoleted due to no activity on 2024/11/10 09:01
upstream KASAN: slab-use-after-free Read in load_firmware_cb (2) usb media 19 C 5 81d 349d 0/29 upstream: reported C repro on 2025/03/30 07:21
upstream KASAN: slab-use-after-free Read in load_firmware_cb media 19 4 536d 590d 0/29 auto-obsoleted due to no activity on 2024/12/23 23:36

Sample crash report:
kobject_add_internal failed for firmware (error: -2 parent: 1-1:0.0)
firmware xc3028-v27.fw: fw_load_sysfs_fallback: device_register failed
==================================================================
BUG: KASAN: use-after-free in load_firmware_cb+0xc0/0x1524 drivers/media/tuners/xc2028.c:1372
Read of size 8 at addr ffff0000c38c1318 by task kworker/1:1/24

CPU: 1 PID: 24 Comm: kworker/1:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Workqueue: events request_firmware_work_func
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 __asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
 load_firmware_cb+0xc0/0x1524 drivers/media/tuners/xc2028.c:1372
 request_firmware_work_func+0xe8/0x19c drivers/base/firmware_loader/main.c:1137
 process_one_work+0x7f8/0x13a4 kernel/workqueue.c:2292
 worker_thread+0x8c4/0xfec kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Allocated by task 24:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0xa0/0xb8 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 tuner_probe+0xc8/0x1698 drivers/media/v4l2-core/tuner-core.c:638
 i2c_device_probe+0x690/0x8fc drivers/i2c/i2c-core-base.c:590
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x39c/0xacc drivers/base/dd.c:639
 __driver_probe_device+0x180/0x310 drivers/base/dd.c:785
 driver_probe_device+0x78/0x324 drivers/base/dd.c:815
 __device_attach_driver+0x290/0x4d4 drivers/base/dd.c:943
 bus_for_each_drv+0x154/0x1e4 drivers/base/bus.c:429
 __device_attach+0x2ac/0x3dc drivers/base/dd.c:1015
 device_initial_probe+0x24/0x34 drivers/base/dd.c:1064
 bus_probe_device+0xbc/0x1c4 drivers/base/bus.c:489
 device_add+0xb04/0xf90 drivers/base/core.c:3697
 device_register+0x28/0x38 drivers/base/core.c:3779
 i2c_new_client_device+0x87c/0xe68 drivers/i2c/i2c-core-base.c:1018
 v4l2_i2c_new_subdev_board+0xb0/0x20c drivers/media/v4l2-core/v4l2-i2c.c:80
 v4l2_i2c_new_subdev+0x130/0x1b8 drivers/media/v4l2-core/v4l2-i2c.c:135
 em28xx_v4l2_init+0x6f4/0x2914 drivers/media/usb/em28xx/em28xx-video.c:2617
 em28xx_init_extension+0x10c/0x1b4 drivers/media/usb/em28xx/em28xx-core.c:1116
 request_module_async+0x68/0x98 drivers/media/usb/em28xx/em28xx-cards.c:3405
 process_one_work+0x7f8/0x13a4 kernel/workqueue.c:2292
 process_scheduled_works kernel/workqueue.c:2355 [inline]
 worker_thread+0xb64/0xfec kernel/workqueue.c:2444
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

Freed by task 24:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:53
 kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
 ____kasan_slab_free+0x148/0x1b0 mm/kasan/common.c:237
 __kasan_slab_free+0x18/0x28 mm/kasan/common.c:245
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x16c/0x1e8 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xbc/0x218 mm/slub.c:3700
 kfree+0xd0/0x1a8 mm/slab_common.c:988
 tuner_remove+0x1d8/0x1f4 drivers/media/v4l2-core/tuner-core.c:791
 i2c_device_remove+0x8c/0x1bc drivers/i2c/i2c-core-base.c:631
 device_remove drivers/base/dd.c:548 [inline]
 __device_release_driver drivers/base/dd.c:1260 [inline]
 device_release_driver_internal+0x3d4/0x6d0 drivers/base/dd.c:1286
 device_release_driver+0x28/0x38 drivers/base/dd.c:1309
 bus_remove_device+0x294/0x384 drivers/base/bus.c:531
 device_del+0x580/0x984 drivers/base/core.c:3885
 device_unregister+0x2c/0xc8 drivers/base/core.c:3928
 i2c_unregister_device+0x114/0x168 drivers/i2c/i2c-core-base.c:1066
 v4l2_i2c_subdev_unregister+0xa8/0xbc drivers/media/v4l2-core/v4l2-i2c.c:28
 v4l2_device_unregister+0x170/0x248 drivers/media/v4l2-core/v4l2-device.c:102
 em28xx_v4l2_init+0x1328/0x2914 drivers/media/usb/em28xx/em28xx-video.c:2898
 em28xx_init_extension+0x10c/0x1b4 drivers/media/usb/em28xx/em28xx-core.c:1116
 request_module_async+0x68/0x98 drivers/media/usb/em28xx/em28xx-cards.c:3405
 process_one_work+0x7f8/0x13a4 kernel/workqueue.c:2292
 process_scheduled_works kernel/workqueue.c:2355 [inline]
 worker_thread+0xb64/0xfec kernel/workqueue.c:2444
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850

The buggy address belongs to the object at ffff0000c38c1000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 792 bytes inside of
 2048-byte region [ffff0000c38c1000, ffff0000c38c1800)

The buggy address belongs to the physical page:
page:00000000c0e769c1 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1038c0
head:00000000c0e769c1 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000122 ffff0000c0002900
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000c38c1200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000c38c1280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff0000c38c1300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff0000c38c1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff0000c38c1400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000005
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000005] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 24 Comm: kworker/1:1 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Workqueue: events request_firmware_work_func
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : load_firmware_cb+0x23c/0x1524 drivers/media/tuners/xc2028.c:1376
lr : load_firmware_cb+0xe4/0x1524 drivers/media/tuners/xc2028.c:1374
sp : ffff80001cab7940
x29: ffff80001cab7a90 x28: ffff00019f57c800 x27: 0000000000000000
x26: dfff800000000000 x25: ffff700003956f3c x24: 1fffe00018718263
x23: ffff80001cab79e0 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: ffff0000c38c1318 x18: ffff800011b8bf60
x17: 0000000000000000 x16: ffff80000804309c x15: 0000000000000000
x14: 0000000000000001 x13: 1ffff00002fbf96c x12: 0000000000ff0100
x11: ff0080000e075b0c x10: 0000000000000000 x9 : ffff80000e075b0c
x8 : 0000000000000005 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff80001cab7318 x4 : ffff8000152f4cc0 x3 : ffff800008193d00
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000028
Call trace:
 load_firmware_cb+0x23c/0x1524 drivers/media/tuners/xc2028.c:1376
 request_firmware_work_func+0xe8/0x19c drivers/base/firmware_loader/main.c:1137
 process_one_work+0x7f8/0x13a4 kernel/workqueue.c:2292
 worker_thread+0x8c4/0xfec kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
Code: b5fff5fb f9403bf6 9100a2c0 d343fc08 (387a6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	b5fff5fb 	cbnz	x27, 0xfffffffffffffebc
   4:	f9403bf6 	ldr	x22, [sp, #112]
   8:	9100a2c0 	add	x0, x22, #0x28
   c:	d343fc08 	lsr	x8, x0, #3
* 10:	387a6908 	ldrb	w8, [x8, x26] <-- trapping instruction

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/12 08:58 linux-6.1.y 8ce36b2849ef 76a109e2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2026/01/19 03:46 linux-6.1.y cd9b81672742 20d37d28 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2026/01/15 16:34 linux-6.1.y bec0e10ee67e d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2025/10/18 17:26 linux-6.1.y c2fda4b3f577 1c8c8cd8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2025/10/18 16:55 linux-6.1.y c2fda4b3f577 1c8c8cd8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2025/12/17 13:33 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
2025/10/18 16:23 linux-6.1.y c2fda4b3f577 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Read in load_firmware_cb
* Struck through repros no longer work on HEAD.