Re: [syzbot] [net?] KASAN: slab-use-after-free Read in unix_stream_read_actor (2)

[Eric Dumazet]

On Wed, Sep 4, 2024 at 5:13 PM syzbot
<syzbot+8811381d455e3e9ec788@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    fbdaffe41adc Merge branch 'am-qt2025-phy-rust'
> git tree:       net-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=13d7c44d980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=996585887acdadb3
> dashboard link: https://syzkaller.appspot.com/bug?extid=8811381d455e3e9ec788
> 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=14b395db980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16d3fc53980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/feaa1b13b490/disk-fbdaffe4.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/8e5dccd0377a/vmlinux-fbdaffe4.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/75151f74f4c9/bzImage-fbdaffe4.xz
>
> Bisection is inconclusive: the first bad commit could be any of:
>
> 06ab21c3cb6e dt-bindings: net: mediatek,net: add top-level constraints
> 70d16e13368c dt-bindings: net: renesas,etheravb: add top-level constraints
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11d42e63980000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8811381d455e3e9ec788@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: slab-use-after-free in unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
> Read of size 4 at addr ffff8880326abcc4 by task syz-executor178/5235
>
> CPU: 0 UID: 0 PID: 5235 Comm: syz-executor178 Not tainted 6.11.0-rc5-syzkaller-00742-gfbdaffe41adc #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:93 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
>  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
>  unix_stream_read_actor+0xa6/0xb0 net/unix/af_unix.c:2959
>  unix_stream_recv_urg+0x1df/0x320 net/unix/af_unix.c:2640
>  unix_stream_read_generic+0x2456/0x2520 net/unix/af_unix.c:2778
>  unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
>  sock_recvmsg_nosec net/socket.c:1046 [inline]
>  sock_recvmsg+0x22f/0x280 net/socket.c:1068
>  ____sys_recvmsg+0x1db/0x470 net/socket.c:2816
>  ___sys_recvmsg net/socket.c:2858 [inline]
>  __sys_recvmsg+0x2f0/0x3e0 net/socket.c:2888
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f5360d6b4e9
> Code: 48 83 c4 28 c3 e8 37 17 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:00007fff29b3a458 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
> RAX: ffffffffffffffda RBX: 00007fff29b3a638 RCX: 00007f5360d6b4e9
> RDX: 0000000000002001 RSI: 0000000020000640 RDI: 0000000000000003
> RBP: 00007f5360dde610 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
> R13: 00007fff29b3a628 R14: 0000000000000001 R15: 0000000000000001
>  </TASK>
>
> Allocated by task 5235:
>  kasan_save_stack mm/kasan/common.c:47 [inline]
>  kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
>  unpoison_slab_object mm/kasan/common.c:312 [inline]
>  __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
>  kasan_slab_alloc include/linux/kasan.h:201 [inline]
>  slab_post_alloc_hook mm/slub.c:3988 [inline]
>  slab_alloc_node mm/slub.c:4037 [inline]
>  kmem_cache_alloc_node_noprof+0x16b/0x320 mm/slub.c:4080
>  __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
>  alloc_skb include/linux/skbuff.h:1320 [inline]
>  alloc_skb_with_frags+0xc3/0x770 net/core/skbuff.c:6528
>  sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2815
>  sock_alloc_send_skb include/net/sock.h:1778 [inline]
>  queue_oob+0x108/0x680 net/unix/af_unix.c:2198
>  unix_stream_sendmsg+0xd24/0xf80 net/unix/af_unix.c:2351
>  sock_sendmsg_nosec net/socket.c:730 [inline]
>  __sock_sendmsg+0x221/0x270 net/socket.c:745
>  ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597
>  ___sys_sendmsg net/socket.c:2651 [inline]
>  __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2680
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> Freed by task 5235:
>  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:2252 [inline]
>  slab_free mm/slub.c:4473 [inline]
>  kmem_cache_free+0x145/0x350 mm/slub.c:4548
>  unix_stream_read_generic+0x1ef6/0x2520 net/unix/af_unix.c:2917
>  unix_stream_recvmsg+0x22b/0x2c0 net/unix/af_unix.c:2996
>  sock_recvmsg_nosec net/socket.c:1046 [inline]
>  sock_recvmsg+0x22f/0x280 net/socket.c:1068
>  __sys_recvfrom+0x256/0x3e0 net/socket.c:2255
>  __do_sys_recvfrom net/socket.c:2273 [inline]
>  __se_sys_recvfrom net/socket.c:2269 [inline]
>  __x64_sys_recvfrom+0xde/0x100 net/socket.c:2269
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
>  entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> The buggy address belongs to the object at ffff8880326abc80
>  which belongs to the cache skbuff_head_cache of size 240
> The buggy address is located 68 bytes inside of
>  freed 240-byte region [ffff8880326abc80, ffff8880326abd70)
>
> The buggy address belongs to the physical page:
> page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x326ab
> ksm flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
> page_type: 0xfdffffff(slab)
> raw: 00fff00000000000 ffff88801eaee780 ffffea0000b7dc80 dead000000000003
> raw: 0000000000000000 00000000800c000c 00000001fdffffff 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 4686, tgid 4686 (udevadm), ts 32357469485, free_ts 28829011109
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1493
>  prep_new_page mm/page_alloc.c:1501 [inline]
>  get_page_from_freelist+0x2e4c/0x2f10 mm/page_alloc.c:3439
>  __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4695
>  __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
>  alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
>  alloc_slab_page+0x5f/0x120 mm/slub.c:2321
>  allocate_slab+0x5a/0x2f0 mm/slub.c:2484
>  new_slab mm/slub.c:2537 [inline]
>  ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3723
>  __slab_alloc+0x58/0xa0 mm/slub.c:3813
>  __slab_alloc_node mm/slub.c:3866 [inline]
>  slab_alloc_node mm/slub.c:4025 [inline]
>  kmem_cache_alloc_node_noprof+0x1fe/0x320 mm/slub.c:4080
>  __alloc_skb+0x1c3/0x440 net/core/skbuff.c:667
>  alloc_skb include/linux/skbuff.h:1320 [inline]
>  alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289
>  uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
>  kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410
>  kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
>  kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207
>  uevent_store+0x4b/0x70 drivers/base/bus.c:633
>  kernfs_fop_write_iter+0x3a1/0x500 fs/kernfs/file.c:334
>  new_sync_write fs/read_write.c:497 [inline]
>  vfs_write+0xa72/0xc90 fs/read_write.c:590
> 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:1094 [inline]
>  free_unref_page+0xd22/0xea0 mm/page_alloc.c:2612
>  kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:408
>  apply_to_pte_range mm/memory.c:2797 [inline]
>  apply_to_pmd_range mm/memory.c:2841 [inline]
>  apply_to_pud_range mm/memory.c:2877 [inline]
>  apply_to_p4d_range mm/memory.c:2913 [inline]
>  __apply_to_page_range+0x8a8/0xe50 mm/memory.c:2947
>  kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:525
>  purge_vmap_node+0x3e3/0x770 mm/vmalloc.c:2208
>  __purge_vmap_area_lazy+0x708/0xae0 mm/vmalloc.c:2290
>  _vm_unmap_aliases+0x79d/0x840 mm/vmalloc.c:2885
>  change_page_attr_set_clr+0x2fe/0xdb0 arch/x86/mm/pat/set_memory.c:1881
>  change_page_attr_set arch/x86/mm/pat/set_memory.c:1922 [inline]
>  set_memory_nx+0xf2/0x130 arch/x86/mm/pat/set_memory.c:2110
>  free_init_pages arch/x86/mm/init.c:924 [inline]
>  free_kernel_image_pages arch/x86/mm/init.c:943 [inline]
>  free_initmem+0x79/0x110 arch/x86/mm/init.c:970
>  kernel_init+0x31/0x2b0 init/main.c:1476
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> Memory state around the buggy address:
>  ffff8880326abb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8880326abc00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
> >ffff8880326abc80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                            ^
>  ffff8880326abd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
>  ffff8880326abd80: fc fc fc fc fc fc fc fc fa 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.
>
> syzbot will keep track of this issue. See:
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> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
>
> If the report is already addressed, let syzbot know by replying with:
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>
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>
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>
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Another af_unix OOB issue.

Rao can you take a look ?

Thanks.