Subject: RE: [PATCH net 1/2] virtio_net: fix page_to_skb() miss headroom

From: John Fastabend <[email-masked]>
Date: Wed, 15 Mar 2023 14:22:53 -0700

Xuan Zhuo wrote:
> Because headroom is not passed to page_to_skb(), this causes the shinfo
> exceeds the range. Then the frags of shinfo are changed by other process.
> 
> [  157.724634] stack segment: 0000 [#1] PREEMPT SMP NOPTI
> [  157.725358] CPU: 3 PID: 679 Comm: xdp_pass_user_f Tainted: G            E      6.2.0+ #150
> [  157.726401] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/4
> [  157.727820] RIP: 0010:skb_release_data+0x11b/0x180
> [  157.728449] Code: 44 24 02 48 83 c3 01 39 d8 7e be 48 89 d8 48 c1 e0 04 41 80 7d 7e 00 49 8b 6c 04 30 79 0c 48 89 ef e8 89 b
> [  157.730751] RSP: 0018:ffffc90000178b48 EFLAGS: 00010202
> [  157.731383] RAX: 0000000000000010 RBX: 0000000000000001 RCX: 0000000000000000
> [  157.732270] RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff888100dd0b00
> [  157.733117] RBP: 5d5d76010f6e2408 R08: ffff888100dd0b2c R09: 0000000000000000
> [  157.734013] R10: ffffffff82effd30 R11: 000000000000a14e R12: ffff88810981ffc0
> [  157.734904] R13: ffff888100dd0b00 R14: 0000000000000002 R15: 0000000000002310
> [  157.735793] FS:  00007f06121d9740(0000) GS:ffff88842fcc0000(0000) knlGS:0000000000000000
> [  157.736794] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  157.737522] CR2: 00007ffd9a56c084 CR3: 0000000104bda001 CR4: 0000000000770ee0
> [  157.738420] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  157.739283] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [  157.740146] PKRU: 55555554
> [  157.740502] Call Trace:
> [  157.740843]  <IRQ>
> [  157.741117]  kfree_skb_reason+0x50/0x120
> [  157.741613]  __udp4_lib_rcv+0x52b/0x5e0
> [  157.742132]  ip_protocol_deliver_rcu+0xaf/0x190
> [  157.742715]  ip_local_deliver_finish+0x77/0xa0
> [  157.743280]  ip_sublist_rcv_finish+0x80/0x90
> [  157.743834]  ip_list_rcv_finish.constprop.0+0x16f/0x190
> [  157.744493]  ip_list_rcv+0x126/0x140
> [  157.744952]  __netif_receive_skb_list_core+0x29b/0x2c0
> [  157.745602]  __netif_receive_skb_list+0xed/0x160
> [  157.746190]  ? udp4_gro_receive+0x275/0x350
> [  157.746732]  netif_receive_skb_list_internal+0xf2/0x1b0
> [  157.747398]  napi_gro_receive+0xd1/0x210
> [  157.747911]  virtnet_receive+0x75/0x1c0
> [  157.748422]  virtnet_poll+0x48/0x1b0
> [  157.748878]  __napi_poll+0x29/0x1b0
> [  157.749330]  net_rx_action+0x27a/0x340
> [  157.749812]  __do_softirq+0xf3/0x2fb
> [  157.750298]  do_softirq+0xa2/0xd0
> [  157.750745]  </IRQ>
> [  157.751563]  <TASK>
> [  157.752329]  __local_bh_enable_ip+0x6d/0x80
> [  157.753178]  virtnet_xdp_set+0x482/0x860
> [  157.754159]  ? __pfx_virtnet_xdp+0x10/0x10
> [  157.755129]  dev_xdp_install+0xa4/0xe0
> [  157.756033]  dev_xdp_attach+0x20b/0x5e0
> [  157.756933]  do_setlink+0x82e/0xc90
> [  157.757777]  ? __nla_validate_parse+0x12b/0x1e0
> [  157.758744]  rtnl_setlink+0xd8/0x170
> [  157.759549]  ? mod_objcg_state+0xcb/0x320
> [  157.760328]  ? security_capable+0x37/0x60
> [  157.761209]  ? security_capable+0x37/0x60
> [  157.762072]  rtnetlink_rcv_msg+0x145/0x3d0
> [  157.762929]  ? ___slab_alloc+0x327/0x610
> [  157.763754]  ? __alloc_skb+0x141/0x170
> [  157.764533]  ? __pfx_rtnetlink_rcv_msg+0x10/0x10
> [  157.765422]  netlink_rcv_skb+0x58/0x110
> [  157.766229]  netlink_unicast+0x21f/0x330
> [  157.766951]  netlink_sendmsg+0x240/0x4a0
> [  157.767654]  sock_sendmsg+0x93/0xa0
> [  157.768434]  ? sockfd_lookup_light+0x12/0x70
> [  157.769245]  __sys_sendto+0xfe/0x170
> [  157.770079]  ? handle_mm_fault+0xe9/0x2d0
> [  157.770859]  ? preempt_count_add+0x51/0xa0
> [  157.771645]  ? up_read+0x3c/0x80
> [  157.772340]  ? do_user_addr_fault+0x1e9/0x710
> [  157.773166]  ? kvm_read_and_reset_apf_flags+0x49/0x60
> [  157.774087]  __x64_sys_sendto+0x29/0x30
> [  157.774856]  do_syscall_64+0x3c/0x90
> [  157.775518]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [  157.776382] RIP: 0033:0x7f06122def70
> 
> Fixes: 18117a842ab0 ("virtio-net: remove xdp related info from page_to_skb()")
> Signed-off-by: Xuan Zhuo <[email-masked]>
> ---

LGTM thanks.

Acked-by: John Fastabend <[email-masked]>