Message-ID: <CAADnVQKEEqhhqu6qTG7qBgv3t=ouzN8U4ewvAFsLUOG_TRBR8w@mail.gmail.com>
Date: Mon, 25 Nov 2024 16:27:05 -0800
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: syzbot <syzbot+7d9959e6503e8ffc8558@...kaller.appspotmail.com>
Cc: andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org, 
	daniel@...earbox.net, eddyz87@...il.com, haoluo@...gle.com, 
	john.fastabend@...il.com, jolsa@...nel.org, kpsingh@...nel.org, 
	linux-kernel@...r.kernel.org, martin.lau@...ux.dev, sdf@...ichev.me, 
	song@...nel.org, syzkaller-bugs@...glegroups.com, yonghong.song@...ux.dev
Subject: Re: [syzbot] [bpf?] KASAN: vmalloc-out-of-bounds Write in vrealloc_noprof

The issue is understood.
Commit 3ddc2fefe6f3 ("mm: vmalloc: implement vrealloc()") is buggy.

Fix is wip.

Same as the other syzbot report.

On Sun, Nov 24, 2024 at 6:50 PM syzbot
<syzbot+7d9959e6503e8ffc8558@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    ac24e26aa08f Add linux-next specific files for 20241120
> git tree:       linux-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=14d91b78580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=45719eec4c74e6ba
> dashboard link: https://syzkaller.appspot.com/bug?extid=7d9959e6503e8ffc8558
> 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=124d8ec0580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1425a75f980000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9c6bcf3605c7/disk-ac24e26a.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/4ce96eb398a9/vmlinux-ac24e26a.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9a22aac22c90/bzImage-ac24e26a.xz
>
> The issue was bisected to:
>
> commit 96a30e469ca1d2b8cc7811b40911f8614b558241
> Author: Andrii Nakryiko <andrii@...nel.org>
> Date:   Fri Nov 15 00:13:03 2024 +0000
>
>     bpf: use common instruction history across all states
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=102bd930580000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=122bd930580000
> console output: https://syzkaller.appspot.com/x/log.txt?x=142bd930580000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+7d9959e6503e8ffc8558@...kaller.appspotmail.com
> Fixes: 96a30e469ca1 ("bpf: use common instruction history across all states")
>
> ==================================================================
> BUG: KASAN: vmalloc-out-of-bounds in vrealloc_noprof+0x340/0x3a0 mm/vmalloc.c:4095
> Write of size 2097120 at addr ffffc90004c00020 by task syz-executor132/5834
>
> CPU: 1 UID: 0 PID: 5834 Comm: syz-executor132 Not tainted 6.12.0-next-20241120-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
>  print_address_description mm/kasan/report.c:378 [inline]
>  print_report+0x169/0x550 mm/kasan/report.c:489
>  kasan_report+0x143/0x180 mm/kasan/report.c:602
>  kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
>  __asan_memset+0x23/0x50 mm/kasan/shadow.c:84
>  vrealloc_noprof+0x340/0x3a0 mm/vmalloc.c:4095
>  push_insn_history+0x16c/0x6a0 kernel/bpf/verifier.c:3571
>  check_mem_access+0xf30/0x2240 kernel/bpf/verifier.c:7267
>  do_check+0x7d97/0xfcd0 kernel/bpf/verifier.c:18703
>  do_check_common+0x1564/0x2010 kernel/bpf/verifier.c:21848
>  do_check_main kernel/bpf/verifier.c:21939 [inline]
>  bpf_check+0x19380/0x1f1b0 kernel/bpf/verifier.c:22656
>  bpf_prog_load+0x1667/0x20f0 kernel/bpf/syscall.c:2947
>  __sys_bpf+0x4ee/0x810 kernel/bpf/syscall.c:5790
>  __do_sys_bpf kernel/bpf/syscall.c:5897 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:5895 [inline]
>  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5895
>  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: 0033:0x7fae10fcf269
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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:00007ffdf2bc3148 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fae10fcf269
> RDX: 0000000000000090 RSI: 0000000020000840 RDI: 0000000000000005
> RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000000a0
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>  </TASK>
>
> The buggy address belongs to the virtual mapping at
>  [ffffc90004800000, ffffc90004e01000) created by:
>  kvrealloc_noprof+0xc7/0x120 mm/util.c:747
>
> The buggy address belongs to the physical page:
> page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6c600
> flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
> raw: 0000000000000000 0000000000000000 00000001ffffffff 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 0x102cc2(GFP_HIGHUSER|__GFP_NOWARN), pid 5834, tgid 5834 (syz-executor132), ts 114573563417, free_ts 25588986996
>  set_page_owner include/linux/page_owner.h:32 [inline]
>  post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1556
>  prep_new_page mm/page_alloc.c:1564 [inline]
>  get_page_from_freelist+0x3725/0x3870 mm/page_alloc.c:3510
>  __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4787
>  alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
>  vm_area_alloc_pages mm/vmalloc.c:3589 [inline]
>  __vmalloc_area_node mm/vmalloc.c:3667 [inline]
>  __vmalloc_node_range_noprof+0x9c9/0x1380 mm/vmalloc.c:3844
>  __kvmalloc_node_noprof+0x142/0x190 mm/util.c:672
>  kvrealloc_noprof+0xc7/0x120 mm/util.c:747
>  push_insn_history+0x16c/0x6a0 kernel/bpf/verifier.c:3571
>  check_mem_access+0xf30/0x2240 kernel/bpf/verifier.c:7267
>  do_check+0x7d97/0xfcd0 kernel/bpf/verifier.c:18703
>  do_check_common+0x1564/0x2010 kernel/bpf/verifier.c:21848
>  do_check_main kernel/bpf/verifier.c:21939 [inline]
>  bpf_check+0x19380/0x1f1b0 kernel/bpf/verifier.c:22656
>  bpf_prog_load+0x1667/0x20f0 kernel/bpf/syscall.c:2947
>  __sys_bpf+0x4ee/0x810 kernel/bpf/syscall.c:5790
>  __do_sys_bpf kernel/bpf/syscall.c:5897 [inline]
>  __se_sys_bpf kernel/bpf/syscall.c:5895 [inline]
>  __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5895
>  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> 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:1127 [inline]
>  free_unref_page+0xdf9/0x1140 mm/page_alloc.c:2693
>  free_contig_range+0x152/0x550 mm/page_alloc.c:6666
>  destroy_args+0x92/0x910 mm/debug_vm_pgtable.c:1017
>  debug_vm_pgtable+0x4be/0x550 mm/debug_vm_pgtable.c:1397
>  do_one_initcall+0x248/0x880 init/main.c:1266
>  do_initcall_level+0x157/0x210 init/main.c:1328
>  do_initcalls+0x3f/0x80 init/main.c:1344
>  kernel_init_freeable+0x435/0x5d0 init/main.c:1577
>  kernel_init+0x1d/0x2b0 init/main.c:1466
>  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:
>  ffffc90004bfff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>  ffffc90004bfff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >ffffc90004c00000: 00 00 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>                                ^
>  ffffc90004c00080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>  ffffc90004c00100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ==================================================================
>
>
> ---
> 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@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup

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