[PATCH] vhost: fix OOB access for invalid vid

[Maxime Coquelin]

On 2/28/23 09:27, David Marchand wrote:
> On Mon, Feb 27, 2023 at 5:19 PM Maxime Coquelin
> <maxime.coquelin at 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 at dpdk.org
>>>
>>> Signed-off-by: David Marchand <david.marchand at 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 ? :-)).

I can add it while applying.

Thanks!
Maxime

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