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.
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.
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>
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