Re: [syzbot] [bpf?] KASAN: slab-use-after-free Read in bpf_link_free

From: Andrii Nakryiko
Date: Thu Apr 04 2024 - 17:25:20 EST

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In reply to: syzbot: "[syzbot] [bpf?] KASAN: slab-use-after-free Read in bpf_link_free"
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On Thu, Apr 4, 2024 at 2:19 PM syzbot
<syzbot+b3851d693eb8edda5c7d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 727900b675b7 Add linux-next specific files for 20240403
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=17bf53c5180000
> kernel config: https://syzkaller.appspot.com/x/.config?x=afcaf46d374cec8c
> dashboard link: https://syzkaller.appspot.com/bug?extid=b3851d693eb8edda5c7d
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/f8fb4daa7a83/disk-727900b6.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d2a6994aee53/vmlinux-727900b6.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6759e5411c39/bzImage-727900b6.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b3851d693eb8edda5c7d@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: slab-use-after-free in bpf_link_free+0x234/0x2d0 kernel/bpf/syscall.c:3065
> Read of size 8 at addr ffff88802e688c10 by task syz-executor.3/5206
>

syz fix: bpf: support deferring bpf_link dealloc to after RCU grace period

> CPU: 0 PID: 5206 Comm: syz-executor.3 Not tainted 6.9.0-rc2-next-20240403-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
> 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_link_free+0x234/0x2d0 kernel/bpf/syscall.c:3065
> bpf_link_put_direct kernel/bpf/syscall.c:3093 [inline]
> bpf_link_release+0x7b/0x90 kernel/bpf/syscall.c:3100
> __fput+0x429/0x8a0 fs/file_table.c:422
> 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
> get_signal+0x16a1/0x1740 kernel/signal.c:2911
> arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
> exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
> exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
> __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
> syscall_exit_to_user_mode+0xc9/0x360 kernel/entry/common.c:218
> do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
> RIP: 0033:0x7f803547dde9
> Code: Unable to access opcode bytes at 0x7f803547ddbf.
> RSP: 002b:00007f80361c80c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: 0000000000000006 RBX: 00007f80355abf80 RCX: 00007f803547dde9
> RDX: 0000000000000010 RSI: 0000000020000040 RDI: 0000000000000011
> RBP: 00007f80354ca47a R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 000000000000000b R14: 00007f80355abf80 R15: 00007fff8c6d4fc8
> </TASK>
>
> Allocated by task 5206:
> 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_noprof+0x19c/0x2b0 mm/slub.c:4100
> kmalloc_noprof include/linux/slab.h:660 [inline]
> kzalloc_noprof include/linux/slab.h:775 [inline]
> bpf_raw_tp_link_attach+0x2a0/0x6e0 kernel/bpf/syscall.c:3845
> bpf_raw_tracepoint_open+0x1c2/0x240 kernel/bpf/syscall.c:3892
> __sys_bpf+0x3c0/0x810 kernel/bpf/syscall.c:5702
> __do_sys_bpf kernel/bpf/syscall.c:5767 [inline]
> __se_sys_bpf kernel/bpf/syscall.c:5765 [inline]
> __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5765
> do_syscall_64+0xfb/0x240
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
>
> Freed by task 24:
> 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:579
> poison_slab_object+0xe0/0x150 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:2180 [inline]
> slab_free mm/slub.c:4384 [inline]
> kfree+0x149/0x350 mm/slub.c:4505
> rcu_do_batch kernel/rcu/tree.c:2559 [inline]
> rcu_core+0xafd/0x1830 kernel/rcu/tree.c:2833
> __do_softirq+0x2c6/0x980 kernel/softirq.c:554
>
> Last potentially related work creation:
> kasan_save_stack+0x3f/0x60 mm/kasan/common.c:47
> __kasan_record_aux_stack+0xac/0xc0 mm/kasan/generic.c:541
> __call_rcu_common kernel/rcu/tree.c:3096 [inline]
> call_rcu+0x167/0xa70 kernel/rcu/tree.c:3200
> bpf_link_free+0x1f8/0x2d0 kernel/bpf/syscall.c:3063
> bpf_link_put_direct kernel/bpf/syscall.c:3093 [inline]
> bpf_link_release+0x7b/0x90 kernel/bpf/syscall.c:3100
> __fput+0x429/0x8a0 fs/file_table.c:422
> 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
> get_signal+0x16a1/0x1740 kernel/signal.c:2911
> arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
> exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
> exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
> __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
> syscall_exit_to_user_mode+0xc9/0x360 kernel/entry/common.c:218
> do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
>
> The buggy address belongs to the object at ffff88802e688c00
> which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 16 bytes inside of
> freed 128-byte region [ffff88802e688c00, ffff88802e688c80)
>
> The buggy address belongs to the physical page:
> page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2e688
> flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
> page_type: 0xffffefff(slab)
> raw: 00fff80000000000 ffff8880150418c0 ffffea0000b40100 dead000000000002
> raw: 0000000000000000 0000000000100010 00000001ffffefff 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 4551, tgid 587604050 (udevadm), ts 4551, free_ts 25547020786
> set_page_owner include/linux/page_owner.h:32 [inline]
> post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1490
> prep_new_page mm/page_alloc.c:1498 [inline]
> get_page_from_freelist+0x2e7e/0x2f40 mm/page_alloc.c:3454
> __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4712
> __alloc_pages_node_noprof include/linux/gfp.h:244 [inline]
> alloc_pages_node_noprof include/linux/gfp.h:271 [inline]
> alloc_slab_page+0x5f/0x120 mm/slub.c:2249
> allocate_slab+0x5a/0x2e0 mm/slub.c:2412
> new_slab mm/slub.c:2465 [inline]
> ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3615
> __slab_alloc+0x58/0xa0 mm/slub.c:3705
> __slab_alloc_node mm/slub.c:3758 [inline]
> slab_alloc_node mm/slub.c:3936 [inline]
> kmalloc_trace_noprof+0x1d5/0x2b0 mm/slub.c:4095
> kmalloc_noprof include/linux/slab.h:660 [inline]
> kzalloc_noprof include/linux/slab.h:775 [inline]
> kernfs_get_open_node fs/kernfs/file.c:525 [inline]
> kernfs_fop_open+0x800/0xcd0 fs/kernfs/file.c:693
> do_dentry_open+0x907/0x15a0 fs/open.c:955
> do_open fs/namei.c:3642 [inline]
> path_openat+0x2860/0x3240 fs/namei.c:3799
> do_filp_open+0x235/0x490 fs/namei.c:3826
> do_sys_openat2+0x13e/0x1d0 fs/open.c:1406
> do_sys_open fs/open.c:1421 [inline]
> __do_sys_openat fs/open.c:1437 [inline]
> __se_sys_openat fs/open.c:1432 [inline]
> __x64_sys_openat+0x247/0x2a0 fs/open.c:1432
> do_syscall_64+0xfb/0x240
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
> page last free pid 4544 tgid 4544 stack trace:
> reset_page_owner include/linux/page_owner.h:25 [inline]
> free_pages_prepare mm/page_alloc.c:1110 [inline]
> free_unref_page+0xd3c/0xec0 mm/page_alloc.c:2617
> discard_slab mm/slub.c:2511 [inline]
> __put_partials+0xeb/0x130 mm/slub.c:2980
> put_cpu_partial+0x17c/0x250 mm/slub.c:3055
> __slab_free+0x2ea/0x3d0 mm/slub.c:4254
> qlink_free mm/kasan/quarantine.c:163 [inline]
> qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179
> kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
> __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
> kasan_slab_alloc include/linux/kasan.h:201 [inline]
> slab_post_alloc_hook mm/slub.c:3888 [inline]
> slab_alloc_node mm/slub.c:3948 [inline]
> kmem_cache_alloc_node_noprof+0x16b/0x310 mm/slub.c:3991
> kmalloc_reserve+0xa8/0x2a0 net/core/skbuff.c:577
> __alloc_skb+0x1f3/0x440 net/core/skbuff.c:668
> netlink_sendmsg+0x637/0xcb0 net/netlink/af_netlink.c:1880
> sock_sendmsg_nosec net/socket.c:730 [inline]
> __sock_sendmsg+0x221/0x270 net/socket.c:745
> ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584
> ___sys_sendmsg net/socket.c:2638 [inline]
> __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667
> do_syscall_64+0xfb/0x240
> entry_SYSCALL_64_after_hwframe+0x72/0x7a
>
> Memory state around the buggy address:
> ffff88802e688b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
> ffff88802e688b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff88802e688c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ^
> ffff88802e688c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88802e688d00: 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.
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>
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>
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>
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In reply to: syzbot: "[syzbot] [bpf?] KASAN: slab-use-after-free Read in bpf_link_free"
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