Subject: KASAN: vmalloc-out-of-bounds Write in pcpu_freelist_populate

From: syzbot <[email-masked]>
Date: Mon, 07 Dec 2020 12:03:11 -0800

Hello,

syzbot found the following issue on:

HEAD commit:    34da8721 selftests/bpf: Test bpf_sk_storage_get in tcp ite..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10c3b837500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3cb098ab0334059f
dashboard link: https://syzkaller.appspot.com/bug?extid=942085bfb8f7a276af1c
compiler:       gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in pcpu_freelist_push_node kernel/bpf/percpu_freelist.c:33 [inline]
BUG: KASAN: vmalloc-out-of-bounds in pcpu_freelist_populate+0x1fe/0x260 kernel/bpf/percpu_freelist.c:114
Write of size 8 at addr ffffc90119e78020 by task syz-executor.4/27988

CPU: 1 PID: 27988 Comm: syz-executor.4 Not tainted 5.10.0-rc6-syzkaller #0
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+0x107/0x163 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x4c8 mm/kasan/report.c:385
 __kasan_report mm/kasan/report.c:545 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:562
 pcpu_freelist_push_node kernel/bpf/percpu_freelist.c:33 [inline]
 pcpu_freelist_populate+0x1fe/0x260 kernel/bpf/percpu_freelist.c:114
 prealloc_init kernel/bpf/hashtab.c:323 [inline]
 htab_map_alloc+0x981/0x1230 kernel/bpf/hashtab.c:507
 find_and_alloc_map kernel/bpf/syscall.c:123 [inline]
 map_create kernel/bpf/syscall.c:829 [inline]
 __do_sys_bpf+0xa81/0x5170 kernel/bpf/syscall.c:4374
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45e0f9
Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f679c7a7c68 EFLAGS: 00000246
 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045e0f9
RDX: 0000000000000040 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 000000000119c068 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119c034
R13: 00007fffd601c75f R14: 00007f679c7a89c0 R15: 000000000119c034

Memory state around the buggy address:
 ffffc90119e77f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90119e77f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90119e78000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                               ^
 ffffc90119e78080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90119e78100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

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