On Mon, 23 Jun 2025 16:58:28 -0700 syzbot <[email protected]> wrote:
> Hello, > > syzbot found the following issue on: > > HEAD commit: 86731a2a651e Linux 6.16-rc3 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1611eb0c580000 According to the above, this came right after a fault injection. I looked at all the kmalloc around the area and I have no idea which one could have caused this by failing. [ 94.712399][ T5826] FAULT_INJECTION: forcing a failure. [ 94.712399][ T5826] name failslab, interval 1, probability 0, space 0, times 1 [ 94.725211][ T5826] CPU: 0 UID: 0 PID: 5826 Comm: syz-executor377 Not tainted 6.16.0-rc3-syzkaller #0 PREEMPT(full) [ 94.725241][ T5826] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 [ 94.725257][ T5826] Call Trace: [ 94.725265][ T5826] <TASK> [ 94.725277][ T5826] dump_stack_lvl+0x16c/0x1f0 [ 94.725334][ T5826] should_fail_ex+0x512/0x640 [ 94.725370][ T5826] ? __kmalloc_cache_noprof+0x57/0x3e0 [ 94.725404][ T5826] should_failslab+0xc2/0x120 [ 94.725426][ T5826] __kmalloc_cache_noprof+0x6a/0x3e0 [ 94.725457][ T5826] ? apply_subsystem_event_filter+0xcd2/0x17a0 [ 94.725493][ T5826] apply_subsystem_event_filter+0xcd2/0x17a0 [ 94.725530][ T5826] ? __might_fault+0x13b/0x190 [ 94.725565][ T5826] ? __pfx_apply_subsystem_event_filter+0x10/0x10 [ 94.725601][ T5826] ? _copy_from_user+0x59/0xd0 [ 94.725640][ T5826] subsystem_filter_write+0x95/0x120 [ 94.725672][ T5826] ? __pfx_subsystem_filter_write+0x10/0x10 [ 94.725700][ T5826] vfs_write+0x2a0/0x1150 [ 94.725739][ T5826] ? __pfx_vfs_write+0x10/0x10 [ 94.725772][ T5826] ? do_sys_openat2+0x157/0x1d0 [ 94.725797][ T5826] ? __pfx_do_sys_openat2+0x10/0x10 [ 94.725821][ T5826] ? find_held_lock+0x2b/0x80 [ 94.725844][ T5826] ? handle_mm_fault+0x2ab/0xd10 [ 94.725884][ T5826] ksys_write+0x12a/0x250 [ 94.725916][ T5826] ? __pfx_ksys_write+0x10/0x10 [ 94.725958][ T5826] do_syscall_64+0xcd/0x490 [ 94.725996][ T5826] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 94.726019][ T5826] RIP: 0033:0x7f0e994323a9 So I thought I found a place that could have caused a UAF bug, but I was mistaken :-p -- Steve > kernel config: https://syzkaller.appspot.com/x/.config?x=4ad206eb0100c6a2 > dashboard link: https://syzkaller.appspot.com/bug?extid=daba72c4af9915e9c894 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for > Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13b16dd4580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17c7bb0c580000 > > Downloadable assets: > disk image: > https://storage.googleapis.com/syzbot-assets/a4314982a0cf/disk-86731a2a.raw.xz > vmlinux: > https://storage.googleapis.com/syzbot-assets/8acf9467ceed/vmlinux-86731a2a.xz > kernel image: > https://storage.googleapis.com/syzbot-assets/dddd9a796b01/bzImage-86731a2a.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: [email protected] > > R10: 0000000000000001 R11: 0000000000000246 R12: 00007f0e9949d618 > R13: 00007ffeb32f2178 R14: 0000000000000001 R15: 0000000000000001 > </TASK> > ================================================================== > BUG: KASAN: slab-use-after-free in free_prog > kernel/trace/trace_events_filter.c:1288 [inline] > BUG: KASAN: slab-use-after-free in __free_filter.part.0+0x153/0x160 > kernel/trace/trace_events_filter.c:1312 > Read of size 8 at addr ffff88801d78a9a0 by task syz-executor377/5826 > > CPU: 0 UID: 0 PID: 5826 Comm: syz-executor377 Not tainted > 6.16.0-rc3-syzkaller #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 05/07/2025 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 > print_address_description mm/kasan/report.c:408 [inline] > print_report+0xcd/0x680 mm/kasan/report.c:521 > kasan_report+0xe0/0x110 mm/kasan/report.c:634 > free_prog kernel/trace/trace_events_filter.c:1288 [inline] > __free_filter.part.0+0x153/0x160 kernel/trace/trace_events_filter.c:1312 > __free_filter kernel/trace/trace_events_filter.c:1309 [inline] > filter_free_subsystem_filters kernel/trace/trace_events_filter.c:1470 > [inline] > apply_subsystem_event_filter+0x1487/0x17a0 > kernel/trace/trace_events_filter.c:2512 > subsystem_filter_write+0x95/0x120 kernel/trace/trace_events.c:2304 > vfs_write+0x2a0/0x1150 fs/read_write.c:684 > ksys_write+0x12a/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f0e994323a9 > Code: 48 83 c4 28 c3 e8 17 1a 00 00 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 73 > 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffeb32f1f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 > RAX: ffffffffffffffda RBX: 00007ffeb32f1fa0 RCX: 00007f0e994323a9 > RDX: 0000000000000009 RSI: 0000000000000000 RDI: 0000000000000004 > RBP: 0000000000000001 R08: 00007ffeb32f1d37 R09: 00007f0e994a0037 > R10: 0000000000000001 R11: 0000000000000246 R12: 00007f0e9949d618 > R13: 00007ffeb32f2178 R14: 0000000000000001 R15: 0000000000000001 > </TASK> > > Allocated by task 13: > kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 > kasan_save_track+0x14/0x30 mm/kasan/common.c:68 > poison_kmalloc_redzone mm/kasan/common.c:377 [inline] > __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 > kmalloc_noprof include/linux/slab.h:905 [inline] > kzalloc_noprof include/linux/slab.h:1039 [inline] > create_new_subsystem kernel/trace/trace_events.c:2742 [inline] > event_subsystem_dir kernel/trace/trace_events.c:2815 [inline] > event_create_dir+0x906/0xd40 kernel/trace/trace_events.c:3037 > __trace_early_add_event_dirs+0xae/0x210 kernel/trace/trace_events.c:4199 > early_event_add_tracer kernel/trace/trace_events.c:4386 [inline] > event_trace_init+0x144/0x1f0 kernel/trace/trace_events.c:4540 > tracer_init_tracefs_work_func+0x12/0x3d0 kernel/trace/trace.c:10480 > process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238 > process_scheduled_works kernel/workqueue.c:3321 [inline] > worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402 > kthread+0x3c5/0x780 kernel/kthread.c:464 > ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > Freed by task 5826: > kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 > kasan_save_track+0x14/0x30 mm/kasan/common.c:68 > kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576 > poison_slab_object mm/kasan/common.c:247 [inline] > __kasan_slab_free+0x51/0x70 mm/kasan/common.c:264 > kasan_slab_free include/linux/kasan.h:233 [inline] > slab_free_hook mm/slub.c:2381 [inline] > slab_free mm/slub.c:4643 [inline] > kfree+0x2b4/0x4d0 mm/slub.c:4842 > __free_filter kernel/trace/trace_events_filter.c:1309 [inline] > free_filter_list+0xa5/0x240 kernel/trace/trace_events_filter.c:1357 > filter_free_subsystem_filters kernel/trace/trace_events_filter.c:1463 > [inline] > apply_subsystem_event_filter+0x12be/0x17a0 > kernel/trace/trace_events_filter.c:2512 > subsystem_filter_write+0x95/0x120 kernel/trace/trace_events.c:2304 > vfs_write+0x2a0/0x1150 fs/read_write.c:684 > ksys_write+0x12a/0x250 fs/read_write.c:738 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xcd/0x490 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > The buggy address belongs to the object at ffff88801d78a9a0 > which belongs to the cache kmalloc-16 of size 16 > The buggy address is located 0 bytes inside of > freed 16-byte region [ffff88801d78a9a0, ffff88801d78a9b0) > > The buggy address belongs to the physical page: > page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d78a > flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff) > page_type: f5(slab) > raw: 00fff00000000000 ffff88801b841640 dead000000000122 0000000000000000 > raw: 0000000000000000 0000000000800080 00000000f5000000 0000000000000000 > page dumped because: kasan: bad access detected > page_owner tracks the page as allocated > page last allocated via order 0, migratetype Unmovable, gfp_mask > 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 > (swapper/0), ts 4520983069, free_ts 0 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1704 > prep_new_page mm/page_alloc.c:1712 [inline] > get_page_from_freelist+0x1321/0x3890 mm/page_alloc.c:3669 > __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:4959 > alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2419 > alloc_slab_page mm/slub.c:2451 [inline] > allocate_slab mm/slub.c:2619 [inline] > new_slab+0x23b/0x330 mm/slub.c:2673 > ___slab_alloc+0xd9c/0x1940 mm/slub.c:3859 > __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3949 > __slab_alloc_node mm/slub.c:4024 [inline] > slab_alloc_node mm/slub.c:4185 [inline] > __do_kmalloc_node mm/slub.c:4327 [inline] > __kmalloc_node_track_caller_noprof+0x2ee/0x510 mm/slub.c:4347 > kvasprintf+0xbc/0x160 lib/kasprintf.c:25 > kvasprintf_const+0x66/0x1a0 lib/kasprintf.c:49 > kobject_set_name_vargs+0x5a/0x140 lib/kobject.c:274 > dev_set_name+0xc7/0x100 drivers/base/core.c:3495 > device_add+0xe59/0x1a70 drivers/base/core.c:3607 > tick_init_sysfs kernel/time/clockevents.c:758 [inline] > clockevents_init_sysfs+0x157/0x2d0 kernel/time/clockevents.c:774 > do_one_initcall+0x120/0x6e0 init/main.c:1274 > do_initcall_level init/main.c:1336 [inline] > do_initcalls init/main.c:1352 [inline] > do_basic_setup init/main.c:1371 [inline] > kernel_init_freeable+0x5c2/0x900 init/main.c:1584 > page_owner free stack trace missing > > Memory state around the buggy address: > ffff88801d78a880: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc > ffff88801d78a900: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc > >ffff88801d78a980: 00 00 fc fc fa fb fc fc 00 00 fc fc 00 00 fc fc > ^ > ffff88801d78aa00: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc > ffff88801d78aa80: 00 00 fc fc 00 00 fc fc 00 00 fc fc 00 00 fc fc > ================================================================== > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at [email protected]. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want syzbot to run the reproducer, reply with: > #syz test: git://repo/address.git branch-or-commit-hash > If you attach or paste a git patch, syzbot will apply it before testing. > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup
