[syzbot] BUG: missing reserved tailroom

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: de55c9a1967c Merge branch 'Add support for transmitting pa..
git tree: bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14ce88ad700000
kernel config: https://syzkaller.appspot.com/x/.config?x=2fa13781bcea50fc
dashboard link: https://syzkaller.appspot.com/bug?extid=0e91362d99386dc5de99
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=11f36345700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14c8ca65700000

The issue was bisected to:

commit b530e9e1063ed2b817eae7eec6ed2daa8be11608
Author: Toke Høiland-Jørgensen <to...@redhat.com>
Date: Wed Mar 9 10:53:42 2022 +0000

bpf: Add "live packet" mode for XDP in BPF_PROG_RUN

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17696e55700000
final oops: https://syzkaller.appspot.com/x/report.txt?x=14e96e55700000
console output: https://syzkaller.appspot.com/x/log.txt?x=10e96e55700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0e9136...@syzkaller.appspotmail.com
Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN")

------------[ cut here ]------------
XDP_WARN: xdp_update_frame_from_buff(line:274): Driver BUG: missing reserved tailroom
WARNING: CPU: 0 PID: 3590 at net/core/xdp.c:599 xdp_warn+0x28/0x30 net/core/xdp.c:599
Modules linked in:
CPU: 0 PID: 3590 Comm: syz-executor167 Not tainted 5.17.0-rc6-syzkaller-01958-gde55c9a1967c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:xdp_warn+0x28/0x30 net/core/xdp.c:599
Code: 40 00 41 55 49 89 fd 41 54 41 89 d4 55 48 89 f5 e8 2d 08 3a fa 4c 89 e9 44 89 e2 48 89 ee 48 c7 c7 80 ea b0 8a e8 ef c7 cd 01 <0f> 0b 5d 41 5c 41 5d c3 55 53 48 89 fb e8 06 08 3a fa 48 8d 7b ec
RSP: 0018:ffffc9000370f6f8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff888018d8a198 RCX: 0000000000000000
RDX: ffff88802272d700 RSI: ffffffff815fe2c8 RDI: fffff520006e1ed1
RBP: ffffffff8ab54aa0 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff815f895e R11: 0000000000000000 R12: 0000000000000112
R13: ffffffff8ab54780 R14: ffff888018d8a000 R15: ffff888018d8ae98
FS: 000055555694a300(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 000000007255a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
xdp_update_frame_from_buff include/net/xdp.h:274 [inline]
xdp_update_frame_from_buff include/net/xdp.h:260 [inline]
xdp_test_run_init_page+0x3f1/0x500 net/bpf/test_run.c:143
page_pool_set_pp_info net/core/page_pool.c:268 [inline]
__page_pool_alloc_pages_slow+0x269/0x1050 net/core/page_pool.c:339
page_pool_alloc_pages+0xb6/0x100 net/core/page_pool.c:372
page_pool_dev_alloc_pages include/net/page_pool.h:197 [inline]
xdp_test_run_batch net/bpf/test_run.c:280 [inline]
bpf_test_run_xdp_live+0x53a/0x18c0 net/bpf/test_run.c:363
bpf_prog_test_run_xdp+0x8f6/0x1440 net/bpf/test_run.c:1317
bpf_prog_test_run kernel/bpf/syscall.c:3363 [inline]
__sys_bpf+0x1858/0x59a0 kernel/bpf/syscall.c:4665
__do_sys_bpf kernel/bpf/syscall.c:4751 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4749 [inline]
__x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4749
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: 0033:0x7fc3679a71f9
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:00007ffdd3b6d268 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc3679a71f9
RDX: 0000000000000048 RSI: 0000000020000000 RDI: 000000000000000a
RBP: 00007fc36796b1e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc36796b270
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>


---
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[Martin KaFai Lau]

Toke, please take a look.

[Toke Høiland-Jørgensen]

Right, I see the problem; will send a fix!

-Toke