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Date:   Thu, 3 Feb 2022 19:11:38 +0100
From:   Lorenzo Bianconi <lorenzo@kernel.org>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     syzbot <syzbot+6d70ca7438345077c549@syzkaller.appspotmail.com>,
        Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@redhat.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>, bpf <bpf@vger.kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "David S. Miller" <davem@davemloft.net>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        Martin KaFai Lau <kafai@fb.com>,
        KP Singh <kpsingh@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Song Liu <songliubraving@fb.com>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Yonghong Song <yhs@fb.com>
Subject: Re: [syzbot] KASAN: slab-out-of-bounds Write in bpf_prog_test_run_xdp
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> Lorenzo, please take a look. I suspect it's xdp frags related.

Hi Alexei,

do you think it is worth to add a test for this condition in
test_xdp_update_frags()?

Regards,
Lorenzo

>=20
> On Wed, Feb 2, 2022 at 5:05 AM syzbot
> <syzbot+6d70ca7438345077c549@syzkaller.appspotmail.com> wrote:
> >
> > syzbot has found a reproducer for the following issue on:
> >
> > HEAD commit:    dd5152ab338c Merge branch 'bpf-btf-dwarf5'
> > git tree:       bpf-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=3D15b770dbb00=
000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=3Db210f94c3ec=
14b22
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D6d70ca7438345=
077c549
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binu=
tils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=3D10044d987=
00000
> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=3D1613fa8fb00=
000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the co=
mmit:
> > Reported-by: syzbot+6d70ca7438345077c549@syzkaller.appspotmail.com
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > BUG: KASAN: slab-out-of-bounds in __skb_frag_set_page include/linux/skb=
uff.h:3242 [inline]
> > BUG: KASAN: slab-out-of-bounds in bpf_prog_test_run_xdp+0x10ac/0x1150 n=
et/bpf/test_run.c:972
> > Write of size 8 at addr ffff88801dc53000 by task syz-executor098/3592
> >
> > CPU: 1 PID: 3592 Comm: syz-executor098 Not tainted 5.16.0-syzkaller-115=
87-gdd5152ab338c #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS=
 Google 01/01/2011
> > Call Trace:
> >  <TASK>
> >  __dump_stack lib/dump_stack.c:88 [inline]
> >  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> >  print_address_description.constprop.0.cold+0x8d/0x336 mm/kasan/report.=
c:255
> >  __kasan_report mm/kasan/report.c:442 [inline]
> >  kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
> >  __skb_frag_set_page include/linux/skbuff.h:3242 [inline]
> >  bpf_prog_test_run_xdp+0x10ac/0x1150 net/bpf/test_run.c:972
> >  bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
> >  __sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
> >  __do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
> >  __se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
> >  __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> > RIP: 0033:0x7fada7c9e229
> > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 c0 ff ff ff f7 d8 64 89 01 48
> > RSP: 002b:00007fff58406588 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fada7c9e229
> > RDX: 0000000000000048 RSI: 0000000020000000 RDI: 000000000000000a
> > RBP: 00007fada7c62210 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fada7c622a0
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >  </TASK>
> >
> > Allocated by task 3592:
> >  kasan_save_stack+0x1e/0x50 mm/kasan/common.c:38
> >  kasan_set_track mm/kasan/common.c:46 [inline]
> >  set_alloc_info mm/kasan/common.c:437 [inline]
> >  ____kasan_kmalloc mm/kasan/common.c:516 [inline]
> >  ____kasan_kmalloc mm/kasan/common.c:475 [inline]
> >  __kasan_kmalloc+0xa9/0xd0 mm/kasan/common.c:525
> >  kmalloc include/linux/slab.h:586 [inline]
> >  kzalloc include/linux/slab.h:715 [inline]
> >  bpf_test_init.isra.0+0x9f/0x150 net/bpf/test_run.c:411
> >  bpf_prog_test_run_xdp+0x2f8/0x1150 net/bpf/test_run.c:941
> >  bpf_prog_test_run kernel/bpf/syscall.c:3356 [inline]
> >  __sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4658
> >  __do_sys_bpf kernel/bpf/syscall.c:4744 [inline]
> >  __se_sys_bpf kernel/bpf/syscall.c:4742 [inline]
> >  __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4742
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> >
> > The buggy address belongs to the object at ffff88801dc52000
> >  which belongs to the cache kmalloc-4k of size 4096
> > The buggy address is located 0 bytes to the right of
> >  4096-byte region [ffff88801dc52000, ffff88801dc53000)
> > The buggy address belongs to the page:
> > page:ffffea0000771400 refcount:1 mapcount:0 mapping:0000000000000000 in=
dex:0x0 pfn:0x1dc50
> > head:ffffea0000771400 order:3 compound_mapcount:0 compound_pincount:0
> > flags: 0xfff00000010200(slab|head|node=3D0|zone=3D1|lastcpupid=3D0x7ff)
> > raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888010c42140
> > raw: 0000000000000000 0000000080040004 00000001ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> > page_owner tracks the page as allocated
> > page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c=
0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC)=
, pid 3592, ts 49734537716, free_ts 49716400399
> >  prep_new_page mm/page_alloc.c:2434 [inline]
> >  get_page_from_freelist+0xa72/0x2f50 mm/page_alloc.c:4165
> >  __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5389
> >  alloc_pages+0x1aa/0x310 mm/mempolicy.c:2271
> >  alloc_slab_page mm/slub.c:1799 [inline]
> >  allocate_slab mm/slub.c:1944 [inline]
> >  new_slab+0x28a/0x3b0 mm/slub.c:2004
> >  ___slab_alloc+0x87c/0xe90 mm/slub.c:3018
> >  __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3105
> >  slab_alloc_node mm/slub.c:3196 [inline]
> >  slab_alloc mm/slub.c:3238 [inline]
> >  kmem_cache_alloc_trace+0x289/0x2c0 mm/slub.c:3255
> >  kmalloc include/linux/slab.h:581 [inline]
> >  kzalloc include/linux/slab.h:715 [inline]
> >  ima_calc_file_hash_tfm+0x282/0x3b0 security/integrity/ima/ima_crypto.c=
:477
> >  ima_calc_file_shash security/integrity/ima/ima_crypto.c:515 [inline]
> >  ima_calc_file_hash+0x19d/0x4b0 security/integrity/ima/ima_crypto.c:572
> >  ima_collect_measurement+0x4c9/0x570 security/integrity/ima/ima_api.c:2=
54
> >  process_measurement+0xd37/0x1920 security/integrity/ima/ima_main.c:337
> >  ima_bprm_check+0xd0/0x220 security/integrity/ima/ima_main.c:491
> >  security_bprm_check+0x7d/0xa0 security/security.c:869
> >  search_binary_handler fs/exec.c:1714 [inline]
> >  exec_binprm fs/exec.c:1767 [inline]
> >  bprm_execve fs/exec.c:1836 [inline]
> >  bprm_execve+0x732/0x19b0 fs/exec.c:1798
> >  do_execveat_common+0x5e3/0x780 fs/exec.c:1925
> >  do_execve fs/exec.c:1993 [inline]
> >  __do_sys_execve fs/exec.c:2069 [inline]
> >  __se_sys_execve fs/exec.c:2064 [inline]
> >  __x64_sys_execve+0x8f/0xc0 fs/exec.c:2064
> > page last free stack trace:
> >  reset_page_owner include/linux/page_owner.h:24 [inline]
> >  free_pages_prepare mm/page_alloc.c:1352 [inline]
> >  free_pcp_prepare+0x374/0x870 mm/page_alloc.c:1404
> >  free_unref_page_prepare mm/page_alloc.c:3325 [inline]
> >  free_unref_page+0x19/0x690 mm/page_alloc.c:3404
> >  __unfreeze_partials+0x320/0x340 mm/slub.c:2536
> >  qlink_free mm/kasan/quarantine.c:157 [inline]
> >  qlist_free_all+0x6d/0x160 mm/kasan/quarantine.c:176
> >  kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:283
> >  __kasan_slab_alloc+0xa2/0xc0 mm/kasan/common.c:447
> >  kasan_slab_alloc include/linux/kasan.h:260 [inline]
> >  slab_post_alloc_hook mm/slab.h:732 [inline]
> >  slab_alloc_node mm/slub.c:3230 [inline]
> >  slab_alloc mm/slub.c:3238 [inline]
> >  kmem_cache_alloc+0x202/0x3a0 mm/slub.c:3243
> >  getname_flags.part.0+0x50/0x4f0 fs/namei.c:138
> >  getname_flags+0x9a/0xe0 include/linux/audit.h:323
> >  user_path_at_empty+0x2b/0x60 fs/namei.c:2800
> >  user_path_at include/linux/namei.h:57 [inline]
> >  vfs_statx+0x142/0x390 fs/stat.c:221
> >  vfs_fstatat fs/stat.c:243 [inline]
> >  __do_sys_newfstatat+0x96/0x120 fs/stat.c:412
> >  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> >  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> >  entry_SYSCALL_64_after_hwframe+0x44/0xae
> >
> > Memory state around the buggy address:
> >  ffff88801dc52f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >  ffff88801dc52f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > >ffff88801dc53000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >                    ^
> >  ffff88801dc53080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >  ffff88801dc53100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> >

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