[syzbot] [bpf?] KASAN: vmalloc-out-of-bounds Write in vrealloc_noprof

[syzbot]

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 <and...@kernel.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+7d9959...@syzkaller.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
==================================================================


---
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[Alexei Starovoitov]

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

Fix is wip.

Same as the other syzbot report.

[Andrii Nakryiko]

On Mon, Nov 25, 2024 at 4:27 PM Alexei Starovoitov
<alexei.st...@gmail.com> wrote:
>
> The issue is understood.
> Commit 3ddc2fefe6f3 ("mm: vmalloc: implement vrealloc()") is buggy.
>

#syz fix: mm: fix vrealloc()'s KASAN poisoning logic