Subject: Re: [syzbot] WARNING: kmalloc bug in bpf

From: syzbot <[email-masked]>
Date: Sat, 11 Dec 2021 14:33:17 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    229fae38d0fc libbpf: Add "bool skipped" to struct bpf_map
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1519ce4db00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a262045c4c15a9e0
dashboard link: https://syzkaller.appspot.com/bug?extid=cecf5b7071a0dfb76530
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=119b6f3ab00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=176cf805b00000

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

------------[ cut here ]------------
WARNING: CPU: 1 PID: 3597 at mm/util.c:597 kvmalloc_node+0x111/0x120 mm/util.c:597
Modules linked in:
CPU: 1 PID: 3597 Comm: syz-executor773 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kvmalloc_node+0x111/0x120 mm/util.c:597
Code: 01 00 00 00 4c 89 e7 e8 7d f7 0c 00 49 89 c5 e9 69 ff ff ff e8 a0 7e d0 ff 41 89 ed 41 81 cd 00 20 01 00 eb 95 e8 8f 7e d0 ff <0f> 0b e9 4c ff ff ff 0f 1f 84 00 00 00 00 00 55 48 89 fd 53 e8 76
RSP: 0018:ffffc900020ffc58 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 1ffff9200041ff97 RCX: 0000000000000000
RDX: ffff8880766a1d00 RSI: ffffffff81a747e1 RDI: 0000000000000003
RBP: 0000000000102cc0 R08: 000000007fffffff R09: 00000000ffffffff
R10: ffffffff81a7479e R11: 0000000000000000 R12: 00000000fffffffe
R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000000
FS:  0000555556e04300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000140 CR3: 000000001db54000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvmalloc include/linux/slab.h:741 [inline]
 map_lookup_elem kernel/bpf/syscall.c:1090 [inline]
 __sys_bpf+0x3a6b/0x5f10 kernel/bpf/syscall.c:4603
 __do_sys_bpf kernel/bpf/syscall.c:4722 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4720 [inline]
 __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4720
 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: 0033:0x7f6bde27f079
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:00007ffc0cb30c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6bde27f079
RDX: 0000000000000020 RSI: 0000000020000100 RDI: 0000000000000001
RBP: 00007f6bde243060 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6bde2430f0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>