From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Bug 1880355 <1880355@bugs.launchpad.net>,
qemu-devel@nongnu.org, Gerd Hoffmann <kraxel@redhat.com>,
Laszlo Ersek <lersek@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Peter Maydell <peter.maydell@linaro.org>,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Subject: Re: [Bug 1880355] [NEW] Length restrictions for fw_cfg_dma_transfer?
Date: Sun, 24 May 2020 12:30:07 +0200 [thread overview]
Message-ID: <ced59c5e-01e9-9da6-5191-9d34ffa976b0@redhat.com> (raw)
In-Reply-To: <159029353528.907.11982786579949073896.malonedeb@chaenomeles.canonical.com>
On 5/24/20 6:12 AM, Alexander Bulekov wrote:
> Public bug reported:
>
> For me, this takes close to 3 minutes at 100% CPU:
> echo "outl 0x518 0x9596ffff" | ./i386-softmmu/qemu-system-i386 -M q35 -m 32 -nographic -accel qtest -monitor none -serial none -qtest stdio
>
> #0 phys_page_find (d=0x606000035d80, addr=136728041144404) at /exec.c:338
> #1 address_space_lookup_region (d=0x606000035d80, addr=136728041144404, resolve_subpage=true) at /exec.c:363
> #2 address_space_translate_internal (d=0x606000035d80, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, resolve_subpage=true) at /exec.c:382
> #3 flatview_do_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen_out=0x7fff1fc0d090, page_mask_out=0x0, is_write=true, is_mmio=true, target_as=0x7fff1fc0ce10, attrs=...)
> pment/qemu/exec.c:520
> #4 flatview_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, is_write=true, attrs=...) at /exec.c:586
> #5 flatview_write_continue (fv=0x606000035d20, addr=136728041144404, attrs=..., ptr=0x7fff1fc0d660, len=172, addr1=136728041144400, l=172, mr=0x557fd54e77e0 <io_mem_unassigned>)
> pment/qemu/exec.c:3160
> #6 flatview_write (fv=0x606000035d20, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3177
> #7 address_space_write (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3271
> #8 dma_memory_set (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, c=0 '\000', len=1378422272) at /dma-helpers.c:31
> #9 fw_cfg_dma_transfer (s=0x61a000001e80) at /hw/nvram/fw_cfg.c:400
> #10 fw_cfg_dma_mem_write (opaque=0x61a000001e80, addr=4, value=4294940309, size=4) at /hw/nvram/fw_cfg.c:467
> #11 memory_region_write_accessor (mr=0x61a000002200, addr=4, value=0x7fff1fc0e3d0, size=4, shift=0, mask=4294967295, attrs=...) at /memory.c:483
> #12 access_with_adjusted_size (addr=4, value=0x7fff1fc0e3d0, size=4, access_size_min=1, access_size_max=8, access_fn=0x557fd2288c80 <memory_region_write_accessor>, mr=0x61a000002200, attrs=...)
> pment/qemu/memory.c:539
> #13 memory_region_dispatch_write (mr=0x61a000002200, addr=4, data=4294940309, op=MO_32, attrs=...) at /memory.c:1476
> #14 flatview_write_continue (fv=0x606000035f00, addr=1304, attrs=..., ptr=0x7fff1fc0ec40, len=4, addr1=4, l=4, mr=0x61a000002200) at /exec.c:3137
> #15 flatview_write (fv=0x606000035f00, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3177
> #16 address_space_write (as=0x557fd54e7bc0 <address_space_io>, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3271
>
>
> It looks like fw_cfg_dma_transfer gets the address(136728041144064) and length(1378422272) for the read from the value provided as input 4294940309 (0xFFFF9695) which lands in pcbios. Should there be any limits on the length of guest-memory that fw_cfg should populate?
It looks to me a normal behavior for a DMA device. DMA devices have a
different address space view than the CPUs.
Also note the fw_cfg is a generic device, not restricted to the x86 arch.
Maybe this function could use dma_memory_valid() to skip unassigned regions?
WARNING: multiple messages have this Message-ID (diff)
From: "Philippe Mathieu-Daudé" <1880355@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: Re: [Bug 1880355] [NEW] Length restrictions for fw_cfg_dma_transfer?
Date: Sun, 24 May 2020 10:30:07 -0000 [thread overview]
Message-ID: <ced59c5e-01e9-9da6-5191-9d34ffa976b0@redhat.com> (raw)
Message-ID: <20200524103007.yc7VpiQFqlOawuJ_DzzqiRn1g9x5aICxy2WlY90W7Eo@z> (raw)
In-Reply-To: 159029353528.907.11982786579949073896.malonedeb@chaenomeles.canonical.com
On 5/24/20 6:12 AM, Alexander Bulekov wrote:
> Public bug reported:
>
> For me, this takes close to 3 minutes at 100% CPU:
> echo "outl 0x518 0x9596ffff" | ./i386-softmmu/qemu-system-i386 -M q35 -m 32 -nographic -accel qtest -monitor none -serial none -qtest stdio
>
> #0 phys_page_find (d=0x606000035d80, addr=136728041144404) at /exec.c:338
> #1 address_space_lookup_region (d=0x606000035d80, addr=136728041144404, resolve_subpage=true) at /exec.c:363
> #2 address_space_translate_internal (d=0x606000035d80, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, resolve_subpage=true) at /exec.c:382
> #3 flatview_do_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen_out=0x7fff1fc0d090, page_mask_out=0x0, is_write=true, is_mmio=true, target_as=0x7fff1fc0ce10, attrs=...)
> pment/qemu/exec.c:520
> #4 flatview_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, is_write=true, attrs=...) at /exec.c:586
> #5 flatview_write_continue (fv=0x606000035d20, addr=136728041144404, attrs=..., ptr=0x7fff1fc0d660, len=172, addr1=136728041144400, l=172, mr=0x557fd54e77e0 <io_mem_unassigned>)
> pment/qemu/exec.c:3160
> #6 flatview_write (fv=0x606000035d20, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3177
> #7 address_space_write (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3271
> #8 dma_memory_set (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, c=0 '\000', len=1378422272) at /dma-helpers.c:31
> #9 fw_cfg_dma_transfer (s=0x61a000001e80) at /hw/nvram/fw_cfg.c:400
> #10 fw_cfg_dma_mem_write (opaque=0x61a000001e80, addr=4, value=4294940309, size=4) at /hw/nvram/fw_cfg.c:467
> #11 memory_region_write_accessor (mr=0x61a000002200, addr=4, value=0x7fff1fc0e3d0, size=4, shift=0, mask=4294967295, attrs=...) at /memory.c:483
> #12 access_with_adjusted_size (addr=4, value=0x7fff1fc0e3d0, size=4, access_size_min=1, access_size_max=8, access_fn=0x557fd2288c80 <memory_region_write_accessor>, mr=0x61a000002200, attrs=...)
> pment/qemu/memory.c:539
> #13 memory_region_dispatch_write (mr=0x61a000002200, addr=4, data=4294940309, op=MO_32, attrs=...) at /memory.c:1476
> #14 flatview_write_continue (fv=0x606000035f00, addr=1304, attrs=..., ptr=0x7fff1fc0ec40, len=4, addr1=4, l=4, mr=0x61a000002200) at /exec.c:3137
> #15 flatview_write (fv=0x606000035f00, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3177
> #16 address_space_write (as=0x557fd54e7bc0 <address_space_io>, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3271
>
>
> It looks like fw_cfg_dma_transfer gets the address(136728041144064) and length(1378422272) for the read from the value provided as input 4294940309 (0xFFFF9695) which lands in pcbios. Should there be any limits on the length of guest-memory that fw_cfg should populate?
It looks to me a normal behavior for a DMA device. DMA devices have a
different address space view than the CPUs.
Also note the fw_cfg is a generic device, not restricted to the x86 arch.
Maybe this function could use dma_memory_valid() to skip unassigned
regions?
--
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1880355
Title:
Length restrictions for fw_cfg_dma_transfer?
Status in QEMU:
New
Bug description:
For me, this takes close to 3 minutes at 100% CPU:
echo "outl 0x518 0x9596ffff" | ./i386-softmmu/qemu-system-i386 -M q35 -m 32 -nographic -accel qtest -monitor none -serial none -qtest stdio
#0 phys_page_find (d=0x606000035d80, addr=136728041144404) at /exec.c:338
#1 address_space_lookup_region (d=0x606000035d80, addr=136728041144404, resolve_subpage=true) at /exec.c:363
#2 address_space_translate_internal (d=0x606000035d80, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, resolve_subpage=true) at /exec.c:382
#3 flatview_do_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen_out=0x7fff1fc0d090, page_mask_out=0x0, is_write=true, is_mmio=true, target_as=0x7fff1fc0ce10, attrs=...)
pment/qemu/exec.c:520
#4 flatview_translate (fv=0x606000035d20, addr=136728041144404, xlat=0x7fff1fc0d070, plen=0x7fff1fc0d090, is_write=true, attrs=...) at /exec.c:586
#5 flatview_write_continue (fv=0x606000035d20, addr=136728041144404, attrs=..., ptr=0x7fff1fc0d660, len=172, addr1=136728041144400, l=172, mr=0x557fd54e77e0 <io_mem_unassigned>)
pment/qemu/exec.c:3160
#6 flatview_write (fv=0x606000035d20, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3177
#7 address_space_write (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, attrs=..., buf=0x7fff1fc0d660, len=512) at /exec.c:3271
#8 dma_memory_set (as=0x557fd54e7a00 <address_space_memory>, addr=136728041144064, c=0 '\000', len=1378422272) at /dma-helpers.c:31
#9 fw_cfg_dma_transfer (s=0x61a000001e80) at /hw/nvram/fw_cfg.c:400
#10 fw_cfg_dma_mem_write (opaque=0x61a000001e80, addr=4, value=4294940309, size=4) at /hw/nvram/fw_cfg.c:467
#11 memory_region_write_accessor (mr=0x61a000002200, addr=4, value=0x7fff1fc0e3d0, size=4, shift=0, mask=4294967295, attrs=...) at /memory.c:483
#12 access_with_adjusted_size (addr=4, value=0x7fff1fc0e3d0, size=4, access_size_min=1, access_size_max=8, access_fn=0x557fd2288c80 <memory_region_write_accessor>, mr=0x61a000002200, attrs=...)
pment/qemu/memory.c:539
#13 memory_region_dispatch_write (mr=0x61a000002200, addr=4, data=4294940309, op=MO_32, attrs=...) at /memory.c:1476
#14 flatview_write_continue (fv=0x606000035f00, addr=1304, attrs=..., ptr=0x7fff1fc0ec40, len=4, addr1=4, l=4, mr=0x61a000002200) at /exec.c:3137
#15 flatview_write (fv=0x606000035f00, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3177
#16 address_space_write (as=0x557fd54e7bc0 <address_space_io>, addr=1304, attrs=..., buf=0x7fff1fc0ec40, len=4) at /exec.c:3271
It looks like fw_cfg_dma_transfer gets the address(136728041144064) and length(1378422272) for the read from the value provided as input 4294940309 (0xFFFF9695) which lands in pcbios. Should there be any limits on the length of guest-memory that fw_cfg should populate?
Found by libfuzzer
To manage notifications about this bug go to:
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next prev parent reply other threads:[~2020-05-24 10:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-24 4:12 [Bug 1880355] [NEW] Length restrictions for fw_cfg_dma_transfer? Alexander Bulekov
2020-05-24 10:30 ` Philippe Mathieu-Daudé [this message]
2020-05-24 10:30 ` Philippe Mathieu-Daudé
2020-05-24 13:40 ` Peter Maydell
2020-05-24 13:40 ` Peter Maydell
2020-05-24 14:27 ` Philippe Mathieu-Daudé
2020-05-24 14:27 ` Philippe Mathieu-Daudé
2020-05-25 13:59 ` Paolo Bonzini
2020-05-25 9:14 ` Mark Cave-Ayland
2020-05-25 9:14 ` Mark Cave-Ayland
2021-06-10 15:50 ` [Bug 1880355] " Thomas Huth
2021-06-14 23:35 ` Alexander Bulekov
2021-06-15 18:17 ` Thomas Huth
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