Re: [syzbot] KASAN: slab-out-of-bounds Write in bpf_prog_test_run_xdp

From: Lorenzo Bianconi
Date: Thu Feb 03 2022 - 13:11:49 EST

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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

>
> On Wed, Feb 2, 2022 at 5:05 AM syzbot
> <syzbot+6d70ca7438345077c549@xxxxxxxxxxxxxxxxxxxxxxxxx> 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=15b770dbb00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=b210f94c3ec14b22
> > dashboard link: https://syzkaller.appspot.com/bug?extid=6d70ca7438345077c549
> > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10044d98700000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1613fa8fb00000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+6d70ca7438345077c549@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > ==================================================================
> > BUG: KASAN: slab-out-of-bounds in __skb_frag_set_page include/linux/skbuff.h:3242 [inline]
> > BUG: KASAN: slab-out-of-bounds in bpf_prog_test_run_xdp+0x10ac/0x1150 net/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-11587-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 index:0x0 pfn:0x1dc50
> > head:ffffea0000771400 order:3 compound_mapcount:0 compound_pincount:0
> > flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
> > 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 0xd20c0(__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:254
> > 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
> > ==================================================================
> >

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Next message: Janis Schoetterl-Glausch: "[RFC PATCH 1/2] uaccess: Add mechanism for arch specific user access with argument"
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In reply to: Lorenzo Bianconi: "Re: [syzbot] KASAN: slab-out-of-bounds Write in bpf_prog_test_run_xdp"
Next in thread: Alexei Starovoitov: "Re: [syzbot] KASAN: slab-out-of-bounds Write in bpf_prog_test_run_xdp"
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