Re: [PATCH net-next] virtio-net: fix use-after-free in page_to_skb()

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Apr 20, 2021 at 04:00:07PM +0200, Eric Dumazet wrote:
> On Tue, Apr 20, 2021 at 3:48 PM Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > On 4/20/21 2:43 AM, Eric Dumazet wrote:
> 
> > >
> >
> > Unfortunately that doesn't fix the problem for me. With this patch applied
> > on top of next-20210419, I still get the same crash as before:
> >
> > udhcpc: sending discover^M
> > Unable to handle kernel paging request at virtual address 0000000000000004^M
> > udhcpc(169): Oops -1^M
> > pc = [<0000000000000004>]  ra = [<fffffc0000b8c5b8>]  ps = 0000    Not tainted^M
> > pc is at 0x4^M
> > ra is at napi_gro_receive+0x68/0x150^M
> > v0 = 0000000000000000  t0 = 0000000000000008  t1 = 0000000000000000^M
> > t2 = 0000000000000000  t3 = 000000000000000e  t4 = 0000000000000038^M
> > t5 = 000000000000ffff  t6 = fffffc00002f298a  t7 = fffffc0002c78000^M
> > s0 = fffffc00010b3ca0  s1 = 0000000000000000  s2 = fffffc00011267e0^M
> > s3 = 0000000000000000  s4 = fffffc00025f2008  s5 = fffffc00002f2940^M
> > s6 = fffffc00025f2040^M
> > a0 = fffffc00025f2008  a1 = fffffc00002f2940  a2 = fffffc0002ca000c^M
> > a3 = fffffc00000250d0  a4 = 0000000effff0008  a5 = 0000000000000000^M
> > t8 = fffffc00010b3c80  t9 = fffffc0002ca04cc  t10= 0000000000000000^M
> > t11= 00000000000004c0  pv = fffffc0000b8bc40  at = 0000000000000000^M
> > gp = fffffc00010f9fb8  sp = 00000000df74db09^M
> > Disabling lock debugging due to kernel taint^M
> > Trace:^M
> > [<fffffc0000b8c5b8>] napi_gro_receive+0x68/0x150^M
> > [<fffffc00009b409c>] receive_buf+0x50c/0x1b80^M
> > [<fffffc00009b58b8>] virtnet_poll+0x1a8/0x5b0^M
> > [<fffffc00009b58ec>] virtnet_poll+0x1dc/0x5b0^M
> > [<fffffc0000b8d17c>] __napi_poll+0x4c/0x270^M
> > [<fffffc0000b8d670>] net_rx_action+0x130/0x2c0^M
> > [<fffffc0000bd6cb0>] sch_direct_xmit+0x170/0x360^M
> > [<fffffc0000bd7000>] __qdisc_run+0x160/0x6c0^M
> > [<fffffc0000337b64>] do_softirq+0xa4/0xd0^M
> > [<fffffc0000337ca4>] __local_bh_enable_ip+0x114/0x120^M
> > [<fffffc0000b89554>] __dev_queue_xmit+0x484/0xa60^M
> > [<fffffc0000cd072c>] packet_sendmsg+0xe7c/0x1ba0^M
> > [<fffffc0000b53338>] __sys_sendto+0xf8/0x170^M
> > [<fffffc0000cfec18>] _raw_spin_unlock+0x18/0x30^M
> > [<fffffc0000a9bf7c>] ehci_irq+0x2cc/0x5c0^M
> > [<fffffc0000a71334>] usb_hcd_irq+0x34/0x50^M
> > [<fffffc0000b521bc>] move_addr_to_kernel+0x3c/0x60^M
> > [<fffffc0000b532e4>] __sys_sendto+0xa4/0x170^M
> > [<fffffc0000b533d4>] sys_sendto+0x24/0x40^M
> > [<fffffc0000cfea38>] _raw_spin_lock+0x18/0x30^M
> > [<fffffc0000cfec18>] _raw_spin_unlock+0x18/0x30^M
> > [<fffffc0000325298>] clipper_enable_irq+0x98/0x100^M
> > [<fffffc0000cfec18>] _raw_spin_unlock+0x18/0x30^M
> > [<fffffc0000311514>] entSys+0xa4/0xc0^M
> 
> OK, it would be nice if you could get line number from this stack trace.
> 

Here you are:

napi_gro_receive (net/core/dev.c:6196)
receive_buf (drivers/net/virtio_net.c:1150)
virtnet_poll (drivers/net/virtio_net.c:1414 drivers/net/virtio_net.c:1519)
clipper_srm_device_interrupt (arch/alpha/kernel/sys_dp264.c:256)
virtnet_poll (drivers/net/virtio_net.c:1413 drivers/net/virtio_net.c:1519)
__napi_poll (net/core/dev.c:6962)
net_rx_action (net/core/dev.c:7029 net/core/dev.c:7116)
__qdisc_run (net/sched/sch_generic.c:376 net/sched/sch_generic.c:384)
do_softirq (./include/asm-generic/softirq_stack.h:10 kernel/softirq.c:460 kernel/softirq.c:447)
__local_bh_enable_ip (kernel/softirq.c:384)
__dev_queue_xmit (./include/linux/bottom_half.h:32 ./include/linux/rcupdate.h:746 net/core/dev.c:4272)
packet_sendmsg (net/packet/af_packet.c:3009 net/packet/af_packet.c:3034)
__sys_sendto (net/socket.c:654 net/socket.c:674 net/socket.c:1977)
__d_alloc (fs/dcache.c:1744)
packet_create (net/packet/af_packet.c:1192 net/packet/af_packet.c:3296)
move_addr_to_kernel (./include/linux/uaccess.h:192 net/socket.c:198 net/socket.c:192)
__sys_sendto (net/socket.c:1968)
sys_sendto (net/socket.c:1989 net/socket.c:1985)
sys_bind (net/socket.c:1648 net/socket.c:1646)
entSys (arch/alpha/kernel/entry.S:477)

Guenter