Re: raw_tp+cookie is buggy. Was: [syzbot] [bpf?] [trace?] KASAN: slab-use-after-free Read in bpf_trace_run1

[Andrii Nakryiko]

On Sun, Mar 24, 2024 at 5:07 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> Hi Andrii,
>
> syzbot found UAF in raw_tp cookie series in bpf-next.
> Reverting the whole merge
> 2e244a72cd48 ("Merge branch 'bpf-raw-tracepoint-support-for-bpf-cookie'")
>
> fixes the issue.
>
> Pls take a look.
> See C reproducer below. It splats consistently with CONFIG_KASAN=y
>
> Thanks.

Will do, traveling today, so will be offline for a bit, but will check
first thing afterwards.

>
> On Sun, Mar 24, 2024 at 4:28 PM syzbot
> <syzbot+981935d9485a560bfbcb@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    520fad2e3206 selftests/bpf: scale benchmark counting by us..
> > git tree:       bpf-next
> > console+strace: https://syzkaller.appspot.com/x/log.txt?x=105af946180000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
> > dashboard link: https://syzkaller.appspot.com/bug?extid=981935d9485a560bfbcb
> > compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=114f17a5180000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=162bb7a5180000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/4eef3506c5ce/disk-520fad2e.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/24d60ebe76cc/vmlinux-520fad2e.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/8f883e706550/bzImage-520fad2e.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+981935d9485a560bfbcb@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > ==================================================================
> > BUG: KASAN: slab-use-after-free in __bpf_trace_run kernel/trace/bpf_trace.c:2376 [inline]
> > BUG: KASAN: slab-use-after-free in bpf_trace_run1+0xcb/0x510 kernel/trace/bpf_trace.c:2430
> > Read of size 8 at addr ffff8880290d9918 by task migration/0/19
> >
> > CPU: 0 PID: 19 Comm: migration/0 Not tainted 6.8.0-syzkaller-05233-g520fad2e3206 #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
> > Stopper: 0x0 <- 0x0
> > Call Trace:
> >  <TASK>
> >  __dump_stack lib/dump_stack.c:88 [inline]
> >  dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
> >  print_address_description mm/kasan/report.c:377 [inline]
> >  print_report+0x169/0x550 mm/kasan/report.c:488
> >  kasan_report+0x143/0x180 mm/kasan/report.c:601
> >  __bpf_trace_run kernel/trace/bpf_trace.c:2376 [inline]
> >  bpf_trace_run1+0xcb/0x510 kernel/trace/bpf_trace.c:2430
> >  __traceiter_rcu_utilization+0x74/0xb0 include/trace/events/rcu.h:27
> >  trace_rcu_utilization+0x194/0x1c0 include/trace/events/rcu.h:27
> >  rcu_note_context_switch+0xc7c/0xff0 kernel/rcu/tree_plugin.h:360
> >  __schedule+0x345/0x4a20 kernel/sched/core.c:6635
> >  __schedule_loop kernel/sched/core.c:6813 [inline]
> >  schedule+0x14b/0x320 kernel/sched/core.c:6828
> >  smpboot_thread_fn+0x61e/0xa30 kernel/smpboot.c:160
> >  kthread+0x2f0/0x390 kernel/kthread.c:388
> >  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> >  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
> >  </TASK>
> >
> > Allocated by task 5075:
> >  kasan_save_stack mm/kasan/common.c:47 [inline]
> >  kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
> >  poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
> >  __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
> >  kasan_kmalloc include/linux/kasan.h:211 [inline]
> >  kmalloc_trace+0x1d9/0x360 mm/slub.c:4012
> >  kmalloc include/linux/slab.h:590 [inline]
> >  kzalloc include/linux/slab.h:711 [inline]
> >  bpf_raw_tp_link_attach+0x2a0/0x6e0 kernel/bpf/syscall.c:3816
> >  bpf_raw_tracepoint_open+0x1c2/0x240 kernel/bpf/syscall.c:3863
> >  __sys_bpf+0x3c0/0x810 kernel/bpf/syscall.c:5673
> >  __do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
> >  __se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
> >  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736
> >  do_syscall_64+0xfb/0x240
> >  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> >
> > Freed by task 5075:
> >  kasan_save_stack mm/kasan/common.c:47 [inline]
> >  kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
> >  kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:589
> >  poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
> >  __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
> >  kasan_slab_free include/linux/kasan.h:184 [inline]
> >  slab_free_hook mm/slub.c:2121 [inline]
> >  slab_free mm/slub.c:4299 [inline]
> >  kfree+0x14a/0x380 mm/slub.c:4409
> >  bpf_link_release+0x3b/0x50 kernel/bpf/syscall.c:3071
> >  __fput+0x429/0x8a0 fs/file_table.c:423
> >  task_work_run+0x24f/0x310 kernel/task_work.c:180
> >  exit_task_work include/linux/task_work.h:38 [inline]
> >  do_exit+0xa1b/0x27e0 kernel/exit.c:878
> >  do_group_exit+0x207/0x2c0 kernel/exit.c:1027
> >  __do_sys_exit_group kernel/exit.c:1038 [inline]
> >  __se_sys_exit_group kernel/exit.c:1036 [inline]
> >  __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1036
> >  do_syscall_64+0xfb/0x240
> >  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> >
> > The buggy address belongs to the object at ffff8880290d9900
> >  which belongs to the cache kmalloc-128 of size 128
> > The buggy address is located 24 bytes inside of
> >  freed 128-byte region [ffff8880290d9900, ffff8880290d9980)
> >
> > The buggy address belongs to the physical page:
> > page:ffffea0000a43640 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x290d9
> > anon flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
> > page_type: 0xffffffff()
> > raw: 00fff00000000800 ffff888014c418c0 0000000000000000 0000000000000001
> > raw: 0000000000000000 0000000000100010 00000001ffffffff 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 4527, tgid 4527 (udevd), ts 43150902736, free_ts 43094996342
> >  set_page_owner include/linux/page_owner.h:31 [inline]
> >  post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
> >  prep_new_page mm/page_alloc.c:1540 [inline]
> >  get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
> >  __alloc_pages+0x256/0x680 mm/page_alloc.c:4569
> >  __alloc_pages_node include/linux/gfp.h:238 [inline]
> >  alloc_pages_node include/linux/gfp.h:261 [inline]
> >  alloc_slab_page+0x5f/0x160 mm/slub.c:2190
> >  allocate_slab mm/slub.c:2354 [inline]
> >  new_slab+0x84/0x2f0 mm/slub.c:2407
> >  ___slab_alloc+0xd1b/0x13e0 mm/slub.c:3540
> >  __slab_alloc mm/slub.c:3625 [inline]
> >  __slab_alloc_node mm/slub.c:3678 [inline]
> >  slab_alloc_node mm/slub.c:3850 [inline]
> >  kmalloc_trace+0x267/0x360 mm/slub.c:4007
> >  kmalloc include/linux/slab.h:590 [inline]
> >  kzalloc include/linux/slab.h:711 [inline]
> >  kernfs_get_open_node fs/kernfs/file.c:523 [inline]
> >  kernfs_fop_open+0x803/0xcd0 fs/kernfs/file.c:691
> >  do_dentry_open+0x907/0x15a0 fs/open.c:956
> >  do_open fs/namei.c:3643 [inline]
> >  path_openat+0x2860/0x3240 fs/namei.c:3800
> >  do_filp_open+0x235/0x490 fs/namei.c:3827
> >  do_sys_openat2+0x13e/0x1d0 fs/open.c:1407
> >  do_sys_open fs/open.c:1422 [inline]
> >  __do_sys_openat fs/open.c:1438 [inline]
> >  __se_sys_openat fs/open.c:1433 [inline]
> >  __x64_sys_openat+0x247/0x2a0 fs/open.c:1433
> >  do_syscall_64+0xfb/0x240
> >  entry_SYSCALL_64_after_hwframe+0x6d/0x75
> > page last free pid 4526 tgid 4526 stack trace:
> >  reset_page_owner include/linux/page_owner.h:24 [inline]
> >  free_pages_prepare mm/page_alloc.c:1140 [inline]
> >  free_unref_page_prepare+0x968/0xa90 mm/page_alloc.c:2346
> >  free_unref_page+0x37/0x3f0 mm/page_alloc.c:2486
> >  rcu_do_batch kernel/rcu/tree.c:2196 [inline]
> >  rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2471
> >  __do_softirq+0x2bc/0x943 kernel/softirq.c:554
> >
> > Memory state around the buggy address:
> >  ffff8880290d9800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >  ffff8880290d9880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > >ffff8880290d9900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> >                             ^
> >  ffff8880290d9980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >  ffff8880290d9a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > ==================================================================
> >
> >
> > ---
> > 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@xxxxxxxxxxxxxxxx.
> >
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> >
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> >
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> >
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> >
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