On 3/17/21 5:35 PM, Alexander Bulekov wrote:
> Correction: there was a response suggesting to add padding to ip6_ext_hdr.
Was the response on the public list or the private security one?
If it was public I missed it. On a private list such comment isn't
very helpful if nobody sends patches to fix it. Maybe we need to
review the security list process.
> On 210317 1233, Alexander Bulekov wrote:
>> Just noticed that I also reported this to QEMU-Security on 2020-05-17.
>> The problem was acknowledged, but I don't think there was any
>> communication after that, so I'm not sure whether this is also stuck in
>> some private issue tracker. Seems pretty tame as far as
>> memory-corrputions go, but I'll send a followup to the private report,
>> to see if it went anywhere..
>> -Alex
>>
>> On 210310 1931, Philippe Mathieu-Daudé wrote:
>>> We can't know the caller read enough data in the memory pointed
>>> by ext_hdr to cast it as a ip6_ext_hdr_routing.
>>> Declare rt_hdr on the stack and fill it again from the iovec.
>>>
>>> Since we already checked there is enough data in the iovec buffer,
>>> simply add an assert() call to consume the bytes_read variable.
>>>
>>> This fix a 2 bytes buffer overrun in eth_parse_ipv6_hdr() reported
>>> by QEMU fuzzer:
>>>
>>> $ cat << EOF | ./qemu-system-i386 -M pc-q35-5.0 \
>>> -accel qtest -monitor none \
>>> -serial none -nographic -qtest stdio
>>> outl 0xcf8 0x80001010
>>> outl 0xcfc 0xe1020000
>>> outl 0xcf8 0x80001004
>>> outw 0xcfc 0x7
>>> write 0x25 0x1 0x86
>>> write 0x26 0x1 0xdd
>>> write 0x4f 0x1 0x2b
>>> write 0xe1020030 0x4 0x190002e1
>>> write 0xe102003a 0x2 0x0807
>>> write 0xe1020048 0x4 0x12077cdd
>>> write 0xe1020400 0x4 0xba077cdd
>>> write 0xe1020420 0x4 0x190002e1
>>> write 0xe1020428 0x4 0x3509d807
>>> write 0xe1020438 0x1 0xe2
>>> EOF
>>> =================================================================
>>> ==2859770==ERROR: AddressSanitizer: stack-buffer-overflow on address
>>> 0x7ffdef904902 at pc 0x561ceefa78de bp 0x7ffdef904820 sp 0x7ffdef904818
>>> READ of size 1 at 0x7ffdef904902 thread T0
>>> #0 0x561ceefa78dd in _eth_get_rss_ex_dst_addr net/eth.c:410:17
>>> #1 0x561ceefa41fb in eth_parse_ipv6_hdr net/eth.c:532:17
>>> #2 0x561cef7de639 in net_tx_pkt_parse_headers
>>> hw/net/net_tx_pkt.c:228:14
>>> #3 0x561cef7dbef4 in net_tx_pkt_parse hw/net/net_tx_pkt.c:273:9
>>> #4 0x561ceec29f22 in e1000e_process_tx_desc
>>> hw/net/e1000e_core.c:730:29
>>> #5 0x561ceec28eac in e1000e_start_xmit hw/net/e1000e_core.c:927:9
>>> #6 0x561ceec1baab in e1000e_set_tdt hw/net/e1000e_core.c:2444:9
>>> #7 0x561ceebf300e in e1000e_core_write hw/net/e1000e_core.c:3256:9
>>> #8 0x561cef3cd4cd in e1000e_mmio_write hw/net/e1000e.c:110:5
>>>
>>> Address 0x7ffdef904902 is located in stack of thread T0 at offset 34 in
>>> frame
>>> #0 0x561ceefa320f in eth_parse_ipv6_hdr net/eth.c:486
>>>
>>> This frame has 1 object(s):
>>> [32, 34) 'ext_hdr' (line 487) <== Memory access at offset 34
>>> overflows this variable
>>> HINT: this may be a false positive if your program uses some custom stack
>>> unwind mechanism, swapcontext or vfork
>>> (longjmp and C++ exceptions *are* supported)
>>> SUMMARY: AddressSanitizer: stack-buffer-overflow net/eth.c:410:17 in
>>> _eth_get_rss_ex_dst_addr
>>> Shadow bytes around the buggy address:
>>> 0x10003df188d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df188e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df188f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18910: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
>>> =>0x10003df18920:[02]f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18930: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18940: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18950: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18960: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>> 0x10003df18970: 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
>>> Stack left redzone: f1
>>> Stack right redzone: f3
>>> ==2859770==ABORTING
>>>
>>> Add the corresponding qtest case with the fuzzer reproducer.
>>>
>>> FWIW GCC 11 similarly reported:
>>>
>>> net/eth.c: In function 'eth_parse_ipv6_hdr':
>>> net/eth.c:410:15: error: array subscript 'struct ip6_ext_hdr_routing[0]'
>>> is partly outside array bounds of 'struct ip6_ext_hdr[1]'
>>> [-Werror=array-bounds]
>>> 410 | if ((rthdr->rtype == 2) && (rthdr->segleft == 1)) {
>>> | ~~~~~^~~~~~~
>>> net/eth.c:485:24: note: while referencing 'ext_hdr'
>>> 485 | struct ip6_ext_hdr ext_hdr;
>>> | ^~~~~~~
>>> net/eth.c:410:38: error: array subscript 'struct ip6_ext_hdr_routing[0]'
>>> is partly outside array bounds of 'struct ip6_ext_hdr[1]'
>>> [-Werror=array-bounds]
>>> 410 | if ((rthdr->rtype == 2) && (rthdr->segleft == 1)) {
>>> | ~~~~~^~~~~~~~~
>>> net/eth.c:485:24: note: while referencing 'ext_hdr'
>>> 485 | struct ip6_ext_hdr ext_hdr;
>>> | ^~~~~~~
>>>
>>> Cc: qemu-sta...@nongnu.org
>>> Buglink: https://bugs.launchpad.net/qemu/+bug/1879531
>>> Reported-by: Alexander Bulekov <alx...@bu.edu>
>>> Reported-by: Miroslav Rezanina <mreza...@redhat.com>
>>> Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>
>>> Fixes: eb700029c78 ("net_pkt: Extend packet abstraction as required by
>>> e1000e functionality")
>>> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
>>> ---
>>> net/eth.c | 13 +++++----
>>> tests/qtest/fuzz-e1000e-test.c | 53 ++++++++++++++++++++++++++++++++++
>>> MAINTAINERS | 1 +
>>> tests/qtest/meson.build | 1 +
>>> 4 files changed, 63 insertions(+), 5 deletions(-)
>>> create mode 100644 tests/qtest/fuzz-e1000e-test.c
