syzbot


KASAN: slab-out-of-bounds Read in bpf_int_jit_compile

Status: fixed on 2019/09/06 20:45
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+35101610ff3e83119b1b@syzkaller.appspotmail.com
Fix commit: 7c2e988f400e bpf: fix x64 JIT code generation for jmp to 1st insn
First crash: 1764d, last: 1764d
Cause bisection: introduced by (bisect log) :
commit 2589726d12a1b12eaaa93c7f1ea64287e383c7a5
Author: Alexei Starovoitov <ast@kernel.org>
Date: Sat Jun 15 19:12:20 2019 +0000

  bpf: introduce bounded loops

Crash: KASAN: slab-out-of-bounds Read in do_jit (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH bpf 0/2] bpf: fix bug in x64 JIT 7 (7) 2019/08/01 20:44
KASAN: slab-out-of-bounds Read in bpf_int_jit_compile 0 (1) 2019/07/24 06:28

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in do_jit /arch/x86/net/bpf_jit_comp.c:966 [inline]
BUG: KASAN: slab-out-of-bounds in bpf_int_jit_compile+0x4d19/0x7530 /arch/x86/net/bpf_jit_comp.c:1132
Read of size 4 at addr ffff8880960cc2bc by task syz-executor607/7822

CPU: 0 PID: 7822 Comm: syz-executor607 Not tainted 5.2.0+ #37
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack /lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x2f8 /lib/dump_stack.c:113
 print_address_description+0x75/0x5b0 /mm/kasan/report.c:351
 __kasan_report+0x14b/0x1c0 /mm/kasan/report.c:482
 kasan_report+0x26/0x50 /mm/kasan/common.c:612
 __asan_report_load4_noabort+0x14/0x20 /mm/kasan/generic_report.c:131
 do_jit /arch/x86/net/bpf_jit_comp.c:966 [inline]
 bpf_int_jit_compile+0x4d19/0x7530 /arch/x86/net/bpf_jit_comp.c:1132
 bpf_prog_select_runtime+0x756/0xa50 /kernel/bpf/core.c:1725
 bpf_prog_load /kernel/bpf/syscall.c:1702 [inline]
 __do_sys_bpf+0x7d4e/0xc0e0 /kernel/bpf/syscall.c:2849
 __se_sys_bpf /kernel/bpf/syscall.c:2808 [inline]
 __x64_sys_bpf+0x7a/0x90 /kernel/bpf/syscall.c:2808
 do_syscall_64+0xfe/0x140 /arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4402c9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffeb7a02c18 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402c9
RDX: 0000000000000046 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 00000000006ca018 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000401b50
R13: 0000000000401be0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 7822:
 save_stack /mm/kasan/common.c:69 [inline]
 set_track /mm/kasan/common.c:77 [inline]
 __kasan_kmalloc+0x11c/0x1b0 /mm/kasan/common.c:487
 kasan_kmalloc+0x9/0x10 /mm/kasan/common.c:501
 kmem_cache_alloc_trace+0x215/0x2f0 /mm/slab.c:3550
 kmalloc /./include/linux/slab.h:552 [inline]
 kzalloc /./include/linux/slab.h:748 [inline]
 bpf_int_jit_compile+0x1b2/0x7530 /arch/x86/net/bpf_jit_comp.c:1092
 bpf_prog_select_runtime+0x756/0xa50 /kernel/bpf/core.c:1725
 bpf_prog_load /kernel/bpf/syscall.c:1702 [inline]
 __do_sys_bpf+0x7d4e/0xc0e0 /kernel/bpf/syscall.c:2849
 __se_sys_bpf /kernel/bpf/syscall.c:2808 [inline]
 __x64_sys_bpf+0x7a/0x90 /kernel/bpf/syscall.c:2808
 do_syscall_64+0xfe/0x140 /arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7329:
 save_stack /mm/kasan/common.c:69 [inline]
 set_track /mm/kasan/common.c:77 [inline]
 __kasan_slab_free+0x12a/0x1e0 /mm/kasan/common.c:449
 kasan_slab_free+0xe/0x10 /mm/kasan/common.c:457
 __cache_free /mm/slab.c:3425 [inline]
 kfree+0x115/0x200 /mm/slab.c:3756
 tomoyo_path_perm+0x6cc/0x8b0 /security/tomoyo/file.c:842
 tomoyo_inode_getattr+0x1c/0x20 /security/tomoyo/tomoyo.c:129
 security_inode_getattr+0xd5/0x150 /security/security.c:1182
 vfs_getattr+0x2a/0x6d0 /fs/stat.c:115
 vfs_statx /fs/stat.c:191 [inline]
 vfs_stat /./include/linux/fs.h:3182 [inline]
 __do_sys_newstat /fs/stat.c:341 [inline]
 __se_sys_newstat+0x10c/0x210 /fs/stat.c:337
 __x64_sys_newstat+0x5b/0x70 /fs/stat.c:337
 do_syscall_64+0xfe/0x140 /arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880960cc280
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 28 bytes to the right of
 32-byte region [ffff8880960cc280, ffff8880960cc2a0)
The buggy address belongs to the page:
page:ffffea0002583300 refcount:1 mapcount:0 mapping:ffff8880aa4001c0 index:0xffff8880960ccfc1
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea00027f47c8 ffffea0002a53a48 ffff8880aa4001c0
raw: ffff8880960ccfc1 ffff8880960cc000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880960cc180: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8880960cc200: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
>ffff8880960cc280: 00 00 00 00 fc fc fc fc 00 00 fc fc fc fc fc fc
                                        ^
 ffff8880960cc300: fb fb fb fb fc fc fc fc 00 00 01 fc fc fc fc fc
 ffff8880960cc380: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2019/07/21 03:33 upstream c6dd78fcb8ee 1656845f .config console log report syz C ci-upstream-kasan-gce-smack-root
* Struck through repros no longer work on HEAD.