Message-ID: <26122837c64946d89cb5d0a3a568bdc2b4854ba6.camel@gmail.com>
Date: Wed, 11 Jun 2025 14:40:52 -0700
From: Eduard Zingerman <eddyz87@...il.com>
To: syzbot <syzbot+b5eb72a560b8149a1885@...kaller.appspotmail.com>, 
	andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
 daniel@...earbox.net, 	haoluo@...gle.com, john.fastabend@...il.com,
 jolsa@...nel.org, kpsingh@...nel.org, 	linux-kernel@...r.kernel.org,
 martin.lau@...ux.dev, sdf@...ichev.me, 	song@...nel.org,
 syzkaller-bugs@...glegroups.com, yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] KASAN: slab-use-after-free Read in do_check

On Wed, 2025-06-11 at 05:36 -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    19a60293b992 Add linux-next specific files for 20250611
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=15472d70580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=76ed3656d7159e27
> dashboard link: https://syzkaller.appspot.com/bug?extid=b5eb72a560b8149a1885
> compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16af860c580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=174db60c580000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/c453c11565fa/disk-19a60293.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4034ded42b2e/vmlinux-19a60293.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/5355903cdb8f/bzImage-19a60293.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b5eb72a560b8149a1885@...kaller.appspotmail.com
> 
> ==================================================================
> BUG: KASAN: slab-use-after-free in do_check+0xb388/0xe170 kernel/bpf/verifier.c:19756
> Read of size 1 at addr ffff88801deeef79 by task syz-executor672/5842
> 
> CPU: 1 UID: 0 PID: 5842 Comm: syz-executor672 Not tainted 6.16.0-rc1-next-20250611-syzkaller #0 PREEMPT(full) 
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
> Call Trace:
>  <TASK>
>  dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
>  print_address_description mm/kasan/report.c:408 [inline]
>  print_report+0xd2/0x2b0 mm/kasan/report.c:521
>  kasan_report+0x118/0x150 mm/kasan/report.c:634
>  do_check+0xb388/0xe170 kernel/bpf/verifier.c:19756
>  do_check_common+0x168d/0x20b0 kernel/bpf/verifier.c:22905
>  do_check_main kernel/bpf/verifier.c:22996 [inline]
>  bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162
>  bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972
>  __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978
>  __do_sys_bpf kernel/bpf/syscall.c:6085 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:6083 [inline]
>  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f7586cdbeb9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007ffc2e683128 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7586cdbeb9
> RDX: 0000000000000094 RSI: 0000200000000840 RDI: 0000000000000005
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000006
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>
> 
> Allocated by task 5842:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
>  poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
>  __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
>  kasan_kmalloc include/linux/kasan.h:260 [inline]
>  __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359
>  kmalloc_noprof include/linux/slab.h:905 [inline]
>  kzalloc_noprof include/linux/slab.h:1039 [inline]
>  do_check_common+0x13f/0x20b0 kernel/bpf/verifier.c:22798
>  do_check_main kernel/bpf/verifier.c:22996 [inline]
>  bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162
>  bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972
>  __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978
>  __do_sys_bpf kernel/bpf/syscall.c:6085 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:6083 [inline]
>  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> Freed by task 5842:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
>  kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
>  poison_slab_object mm/kasan/common.c:247 [inline]
>  __kasan_slab_free+0x62/0x70 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+0x18e/0x440 mm/slub.c:4842
>  push_stack+0x247/0x3c0 kernel/bpf/verifier.c:2069
>  check_cond_jmp_op+0x1069/0x2340 kernel/bpf/verifier.c:16562
>  do_check_insn kernel/bpf/verifier.c:19621 [inline]
>  do_check+0x672c/0xe170 kernel/bpf/verifier.c:19755
>  do_check_common+0x168d/0x20b0 kernel/bpf/verifier.c:22905
>  do_check_main kernel/bpf/verifier.c:22996 [inline]
>  bpf_check+0x1381e/0x19e50 kernel/bpf/verifier.c:24162
>  bpf_prog_load+0x1318/0x1930 kernel/bpf/syscall.c:2972
>  __sys_bpf+0x5f1/0x860 kernel/bpf/syscall.c:5978
>  __do_sys_bpf kernel/bpf/syscall.c:6085 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:6083 [inline]
>  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6083
>  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
>  do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> 
> The buggy address belongs to the object at ffff88801deeef00
>  which belongs to the cache kmalloc-192 of size 192
> The buggy address is located 121 bytes inside of
>  freed 192-byte region [ffff88801deeef00, ffff88801deeefc0)
> 
> The buggy address belongs to the physical page:
> page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1deee
> flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
> page_type: f5(slab)
> raw: 00fff00000000000 ffff88801a4413c0 ffffea00006fca40 dead000000000004
> raw: 0000000000000000 0000000000100010 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 2954361175, free_ts 2954343552
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
>  prep_new_page mm/page_alloc.c:1712 [inline]
>  get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
>  __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
>  alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
>  alloc_slab_page mm/slub.c:2451 [inline]
>  allocate_slab+0x8a/0x3b0 mm/slub.c:2619
>  new_slab mm/slub.c:2673 [inline]
>  ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
>  __slab_alloc mm/slub.c:3949 [inline]
>  __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_noprof+0x2fd/0x4e0 mm/slub.c:4334
>  kmalloc_node_noprof include/linux/slab.h:932 [inline]
>  __vmalloc_area_node mm/vmalloc.c:3690 [inline]
>  __vmalloc_node_range_noprof+0x5a9/0x12f0 mm/vmalloc.c:3885
>  vmalloc_huge_node_noprof+0xb3/0xf0 mm/vmalloc.c:4001
>  vmalloc_huge include/linux/vmalloc.h:185 [inline]
>  alloc_large_system_hash+0x2b8/0x5e0 mm/mm_init.c:2515
>  posixtimer_init+0x140/0x270 kernel/time/posix-timers.c:1561
>  do_one_initcall+0x233/0x820 init/main.c:1274
>  do_initcall_level+0x137/0x1f0 init/main.c:1336
>  do_initcalls+0x69/0xd0 init/main.c:1352
>  kernel_init_freeable+0x3d9/0x570 init/main.c:1584
>  kernel_init+0x1d/0x1d0 init/main.c:1474
> page last free pid 1 tgid 1 stack trace:
>  reset_page_owner include/linux/page_owner.h:25 [inline]
>  free_pages_prepare mm/page_alloc.c:1248 [inline]
>  __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
>  __kasan_populate_vmalloc mm/kasan/shadow.c:383 [inline]
>  kasan_populate_vmalloc+0x18a/0x1a0 mm/kasan/shadow.c:417
>  alloc_vmap_area+0xd51/0x1490 mm/vmalloc.c:2084
>  __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3179
>  __vmalloc_node_range_noprof+0x301/0x12f0 mm/vmalloc.c:3845
>  vmalloc_huge_node_noprof+0xb3/0xf0 mm/vmalloc.c:4001
>  vmalloc_huge include/linux/vmalloc.h:185 [inline]
>  alloc_large_system_hash+0x2b8/0x5e0 mm/mm_init.c:2515
>  posixtimer_init+0x140/0x270 kernel/time/posix-timers.c:1561
>  do_one_initcall+0x233/0x820 init/main.c:1274
>  do_initcall_level+0x137/0x1f0 init/main.c:1336
>  do_initcalls+0x69/0xd0 init/main.c:1352
>  kernel_init_freeable+0x3d9/0x570 init/main.c:1584
>  kernel_init+0x1d/0x1d0 init/main.c:1474
>  ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
> 
> Memory state around the buggy address:
>  ffff88801deeee00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffff88801deeee80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
> > ffff88801deeef00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                                                 ^
>  ffff88801deeef80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>  ffff88801deef000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
> 
> 
> ---
> 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 syzkaller@...glegroups.com.
> 
> 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

#syz test: git@...hub.com:kernel-patches/bpf.git 974c296e39c3b2462bbf1f926d5a5db64399359f

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