Re: [PATCH] vhost: fix OOB access for invalid vid

[David Marchand <david.marchand@redhat.com>]

On Mon, Feb 27, 2023 at 5:19 PM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> On 2/27/23 11:59, David Marchand wrote:
> > The net/vhost pmd currently provides a -1 vid when disabling interrupt
> > after a virtio port got disconnected.
> >
> > This can be caught when running with ASan.
> >
> > First, start dpdk-l3fwd-power in interrupt mode with a net/vhost port.
> >
> > $ ./build-clang/examples/dpdk-l3fwd-power -l0,1 --in-memory \
> >       -a 0000:00:00.0 \
> >       --vdev net_vhost0,iface=plop.sock,client=1\
> >       -- \
> >       -p 0x1 \
> >       --interrupt-only \
> >       --config '(0,0,1)' \
> >       --parse-ptype 0
> >
> > Then start testpmd with virtio-user.
> >
> > $ ./build-clang/app/dpdk-testpmd -l0,2 --single-file-segment --in-memory \
> >       -a 0000:00:00.0 \
> >       --vdev net_virtio_user0,path=plop.sock,server=1 \
> >       -- \
> >       -i
> >
> > Finally stop testpmd.
> > ASan then splats in dpdk-l3fwd-power:
> >
> > =================================================================
> > ==3641005==ERROR: AddressSanitizer: global-buffer-overflow on address
> >       0x000005ed0778 at pc 0x000001270f81 bp 0x7fddbd2eee20
> >       sp 0x7fddbd2eee18
> > READ of size 8 at 0x000005ed0778 thread T2
> >      #0 0x1270f80 in get_device .../lib/vhost/vhost.h:801:27
> >      #1 0x1270f80 in rte_vhost_get_vhost_vring .../lib/vhost/vhost.c:951:8
> >      #2 0x3ac95cb in eth_rxq_intr_disable
> >       .../drivers/net/vhost/rte_eth_vhost.c:647:8
> >      #3 0x170e0bf in rte_eth_dev_rx_intr_disable
> >       .../lib/ethdev/rte_ethdev.c:5443:25
> >      #4 0xf72ba7 in turn_on_off_intr .../examples/l3fwd-power/main.c:881:4
> >      #5 0xf71045 in main_intr_loop .../examples/l3fwd-power/main.c:1061:6
> >      #6 0x17f9292 in eal_thread_loop
> >       .../lib/eal/common/eal_common_thread.c:210:9
> >      #7 0x18373f5 in eal_worker_thread_loop .../lib/eal/linux/eal.c:915:2
> >      #8 0x7fddc16ae12c in start_thread (/lib64/libc.so.6+0x8b12c)
> >       (BuildId: 81daba31ee66dbd63efdc4252a872949d874d136)
> >      #9 0x7fddc172fbbf in __GI___clone3 (/lib64/libc.so.6+0x10cbbf)
> >       (BuildId: 81daba31ee66dbd63efdc4252a872949d874d136)
> >
> > 0x000005ed0778 is located 8 bytes to the left of global variable
> >       'vhost_devices' defined in '.../lib/vhost/vhost.c:24'
> >       (0x5ed0780) of size 8192
> > 0x000005ed0778 is located 20 bytes to the right of global variable
> >       'vhost_config_log_level' defined in '.../lib/vhost/vhost.c:2174'
> >       (0x5ed0760) of size 4
> > SUMMARY: AddressSanitizer: global-buffer-overflow
> >       .../lib/vhost/vhost.h:801:27 in get_device
> > Shadow bytes around the buggy address:
> >    0x000080bd2090: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
> >    0x000080bd20a0: f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9 f9
> >    0x000080bd20b0: f9 f9 f9 f9 00 f9 f9 f9 00 f9 f9 f9 00 f9 f9 f9
> >    0x000080bd20c0: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 04 f9 f9 f9
> >    0x000080bd20d0: 00 00 00 00 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00
> > =>0x000080bd20e0: 00 f9 f9 f9 f9 f9 f9 f9 04 f9 f9 f9 04 f9 f9[f9]
> >    0x000080bd20f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >    0x000080bd2100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >    0x000080bd2110: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >    0x000080bd2120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >    0x000080bd2130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> > Shadow byte legend (one shadow byte represents 8 application bytes):
> >    Addressable:           00
> >    Partially addressable: 01 02 03 04 05 06 07
> >    Heap left redzone:       fa
> >    Freed heap region:       fd
> >    Stack left redzone:      f1
> >    Stack mid redzone:       f2
> >    Stack right redzone:     f3
> >    Stack after return:      f5
> >    Stack use after scope:   f8
> >    Global redzone:          f9
> >    Global init order:       f6
> >    Poisoned by user:        f7
> >    Container overflow:      fc
> >    Array cookie:            ac
> >    Intra object redzone:    bb
> >    ASan internal:           fe
> >    Left alloca redzone:     ca
> >    Right alloca redzone:    cb
> > Thread T2 created by T0 here:
> >      #0 0xe98996 in __interceptor_pthread_create
> >       (.examples/dpdk-l3fwd-power+0xe98996)
> >       (BuildId: d0b984a3b0287b9e0f301b73426fa921aeecca3a)
> >      #1 0x1836767 in eal_worker_thread_create .../lib/eal/linux/eal.c:952:6
> >      #2 0x1834b83 in rte_eal_init .../lib/eal/linux/eal.c:1257:9
> >      #3 0xf68902 in main .../examples/l3fwd-power/main.c:2496:8
> >      #4 0x7fddc164a50f in __libc_start_call_main (/lib64/libc.so.6+0x2750f)
> >       (BuildId: 81daba31ee66dbd63efdc4252a872949d874d136)
> >
> > ==3641005==ABORTING
> >
> > More generally, any application passing an incorrect vid would trigger
> > such an OOB access.
> >
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: David Marchand <david.marchand@redhat.com>
> > ---
> > Note: even after this patch, reconnecting the virtio-user port with
> > dpdk-l3fwd-power in interrupt mode still seems broken, as the net/vhost
> > pmd keeps complaining about an issue with rx interrupt fds.
> >
> > ---
> >   lib/vhost/vhost.h | 5 ++++-
> >   1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
> > index 5750f0c005..d9e97280fa 100644
> > --- a/lib/vhost/vhost.h
> > +++ b/lib/vhost/vhost.h
> > @@ -798,7 +798,10 @@ hva_to_gpa(struct virtio_net *dev, uint64_t vva, uint64_t len)
> >   static __rte_always_inline struct virtio_net *
> >   get_device(int vid)
> >   {
> > -     struct virtio_net *dev = vhost_devices[vid];
> > +     struct virtio_net *dev = NULL;
> > +
> > +     if (vid >= 0 && vid < RTE_MAX_VHOST_DEVICE)
>
> Maybe use likely() to help the compiler?

I see no difference in x86 generated code with gcc 12 but I don't mind
adding it (or you can add it while applying ? :-)).


>
> > +             dev = vhost_devices[vid];
> >
> >       if (unlikely(!dev)) {
> >               VHOST_LOG_CONFIG("device", ERR, "(%d) device not found.\n", vid);


-- 
David Marchand