Re: [PATCH] net: eepro100: validate various address values

[Li Qiang <liq3ea@gmail.com>]

Alexander Bulekov <alxndr@bu.edu> 于2021年2月19日周五 上午10:15写道：
>
> On 210219 1006, Li Qiang wrote:
> > Alexander Bulekov <alxndr@bu.edu> 于2021年2月19日周五 上午9:56写道：
> > >
> > > On 210218 1441, Peter Maydell wrote:
> > > > On Thu, 18 Feb 2021 at 14:13, P J P <ppandit@redhat.com> wrote:
> > > > >
> > > > > From: Prasad J Pandit <pjp@fedoraproject.org>
> > > > >
> > > > > While processing controller commands, eepro100 emulator gets
> > > > > command unit(CU) base address OR receive unit (RU) base address
> > > > > OR command block (CB) address from guest. If these values are not
> > > > > checked, it may lead to an infinite loop kind of issues. Add checks
> > > > > to avoid it.
> >
> >
> > So could you please provide a backtrack?
> >
>
> I don't know if you are asking me or Prasad, but here is the stacktrace


Yes, a typical DMA reentry issue.
Any progress to solve these DMA reentry issues? seems more and more
this kind of issues.
Just return from the busy things as a new father and not focus this
quite a time.

Thanks,
Li Qiang

> for the one I provided:
> ==2715275==ERROR: AddressSanitizer: stack-overflow on address
> 0x7ffc5262ba28 (pc 0x55d83b103ac6 bp 0x7ffc5262c270 sp 0x7ffc5262ba30
> T0)
> #0 in __asan_memcpy (qemu-system-i386+0x2aa3ac6)
> #1 in flatview_do_translate ../softmmu/physmem.c:518:12
> #2 in flatview_translate ../softmmu/physmem.c:568:15
> #3 in flatview_read ../softmmu/physmem.c:2878:10
> #4 in address_space_read_full ../softmmu/physmem.c:2892:18
> #5 in dma_memory_rw_relaxed include/sysemu/dma.h:88:12
> #6 in dma_memory_rw include/sysemu/dma.h:127:12
> #7 in pci_dma_rw include/hw/pci/pci.h:803:12
> #8 in pci_dma_read include/hw/pci/pci.h:821:12
> #9 in read_cb ../hw/net/eepro100.c:726:5
> #10 in action_command ../hw/net/eepro100.c:847:9
> #11 in eepro100_cu_command ../hw/net/eepro100.c:969:13
> #12 in eepro100_write_command ../hw/net/eepro100.c:1063:5
> #13 in eepro100_write2 ../hw/net/eepro100.c:1510:9
> #14 in eepro100_write ../hw/net/eepro100.c:1593:9
> #15 in memory_region_write_accessor ../softmmu/memory.c:491:5
> #16 in access_with_adjusted_size ../softmmu/memory.c:552:18
> #17 in memory_region_dispatch_write ../softmmu/memory.c
> #18 in flatview_write_continue ../softmmu/physmem.c:2776:23
> #19 in flatview_write ../softmmu/physmem.c:2816:14
> #20 in address_space_write ../softmmu/physmem.c:2908:18
> #21 in dma_memory_rw_relaxed include/sysemu/dma.h:88:12
> #22 in dma_memory_rw include/sysemu/dma.h:127:12
> #23 in dma_memory_write include/sysemu/dma.h:163:12
> #24 in stw_le_dma include/sysemu/dma.h:259:1
> #25 in stw_le_pci_dma include/hw/pci/pci.h:855:1
> #26 in action_command ../hw/net/eepro100.c:913:9
> #27 in eepro100_cu_command ../hw/net/eepro100.c:969:13
> #28 in eepro100_write_command ../hw/net/eepro100.c:1063:5
> #29 in eepro100_write2 ../hw/net/eepro100.c:1510:9
> #30 in eepro100_write ../hw/net/eepro100.c:1593:9
> ... till there's no more stack ...
>
> >
> > Thanks,
> > Li Qiang
> >
> > > > >
> > > > > Reported-by: Ruhr-University Bochum <bugs-syssec@rub.de>
> > > > > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
> > > > > ---
> > > > >  hw/net/eepro100.c | 8 +++++++-
> > > > >  1 file changed, 7 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/hw/net/eepro100.c b/hw/net/eepro100.c
> > > > > index 16e95ef9cc..afa1c9b2aa 100644
> > > > > --- a/hw/net/eepro100.c
> > > > > +++ b/hw/net/eepro100.c
> > > > > @@ -843,7 +843,8 @@ static void action_command(EEPRO100State *s)
> > > > >          bool bit_i;
> > > > >          bool bit_nc;
> > > > >          uint16_t ok_status = STATUS_OK;
> > > > > -        s->cb_address = s->cu_base + s->cu_offset;
> > > > > +        s->cb_address = s->cu_base + s->cu_offset;  /* uint32_t overflow */
> > > > > +        assert (s->cb_address >= s->cu_base);
> > > >
> > > > We get these values from the guest; you can't just assert() on them.
> > > > You need to do something else.
> > > >
> > > > My reading of the 8255x data sheet is that there is nothing
> > > > in the hardware that forbids the guest from programming the
> > > > device such that the cu_base + cu_offset wraps around:
> > > > http://www.intel.com/content/dam/doc/manual/8255x-10-100-mbps-ethernet-controller-software-dev-manual.pdf
> > > > -- page 30 says that this is all doing 32-bit arithmetic
> > > > on addresses and doesn't say that there is any special case
> > > > handling by the device of overflow of that addition.
> > > >
> > > > Your commit message isn't very clear about what the failure
> > > > case is here, but I think the fix has to be something
> > > > different from this.
> > >
> > > Maybe the infinite loop mentioned in the commit message is actually a
> > > DMA recursion issue? I'm providing a reproducer for a DMA re-entracy
> > > issue below. With this patch applied, the reproducer triggers the
> > > assert(), rather than overflowing the stack, so maybe it is the same
> > > issue?
> > > -Alex
> > >
> > > cat << EOF | ./qemu-system-i386 -display none -machine accel=qtest, -m \
> > > 512M -device i82559er,netdev=net0 -netdev user,id=net0 -nodefaults \
> > > -qtest stdio
> > > outl 0xcf8 0x80001014
> > > outl 0xcfc 0xc000
> > > outl 0xcf8 0x80001010
> > > outl 0xcfc 0xe0020000
> > > outl 0xcf8 0x80001004
> > > outw 0xcfc 0x7
> > > write 0x1ffffc0b 0x1 0x55
> > > write 0x1ffffc0c 0x1 0xfc
> > > write 0x1ffffc0d 0x1 0x46
> > > write 0x1ffffc0e 0x1 0x07
> > > write 0x746fc59 0x1 0x02
> > > write 0x746fc5b 0x1 0x02
> > > write 0x746fc5c 0x1 0xe0
> > > write 0x4 0x1 0x07
> > > write 0x5 0x1 0xfc
> > > write 0x6 0x1 0xff
> > > write 0x7 0x1 0x1f
> > > outw 0xc002 0x20
> > > EOF
> > >
> > > Formatted for committing a regression-test:
> > >
> > > static void test_fuzz(void)
> > > {
> > >     QTestState *s =
> > >         qtest_init("-display none , -m 512M -device i82559er,netdev=net0 "
> > >                    "-netdev user,id=net0 -nodefaults");
> > >     qtest_outl(s, 0xcf8, 0x80001014);
> > >     qtest_outl(s, 0xcfc, 0xc000);
> > >     qtest_outl(s, 0xcf8, 0x80001010);
> > >     qtest_outl(s, 0xcfc, 0xe0020000);
> > >     qtest_outl(s, 0xcf8, 0x80001004);
> > >     qtest_outw(s, 0xcfc, 0x7);
> > >     qtest_bufwrite(s, 0x1ffffc0b, "\x55", 0x1);
> > >     qtest_bufwrite(s, 0x1ffffc0c, "\xfc", 0x1);
> > >     qtest_bufwrite(s, 0x1ffffc0d, "\x46", 0x1);
> > >     qtest_bufwrite(s, 0x1ffffc0e, "\x07", 0x1);
> > >     qtest_bufwrite(s, 0x746fc59, "\x02", 0x1);
> > >     qtest_bufwrite(s, 0x746fc5b, "\x02", 0x1);
> > >     qtest_bufwrite(s, 0x746fc5c, "\xe0", 0x1);
> > >     qtest_bufwrite(s, 0x4, "\x07", 0x1);
> > >     qtest_bufwrite(s, 0x5, "\xfc", 0x1);
> > >     qtest_bufwrite(s, 0x6, "\xff", 0x1);
> > >     qtest_bufwrite(s, 0x7, "\x1f", 0x1);
> > >     qtest_outw(s, 0xc002, 0x20);
> > >     qtest_quit(s);
> > > }
> > >
> > >
> > > >
> > > > thanks
> > > > -- PMM
> > > >
> > >