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

From: syzbot <[email-masked]>
Date: Wed, 02 Feb 2022 05:05:26 -0800

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: [email-masked]

==================================================================
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
==================================================================