Re: [PATCH] net: tulip: Restrict DMA engine to memories

[Jason Wang]

On Sun, Aug 21, 2022 at 8:29 PM Zheyu Ma <zheyuma97@gmail.com> wrote:
>
> The DMA engine is started by I/O access and then itself accesses the
> I/O registers, triggering a reentrancy bug.
>
> The following log can reveal it:
> ==5637==ERROR: AddressSanitizer: stack-overflow
>     #0 0x5595435f6078 in tulip_xmit_list_update qemu/hw/net/tulip.c:673
>     #1 0x5595435f204a in tulip_write qemu/hw/net/tulip.c:805:13
>     #2 0x559544637f86 in memory_region_write_accessor 
> qemu/softmmu/memory.c:492:5
>     #3 0x5595446379fa in access_with_adjusted_size 
> qemu/softmmu/memory.c:554:18
>     #4 0x5595446372fa in memory_region_dispatch_write qemu/softmmu/memory.c
>     #5 0x55954468b74c in flatview_write_continue 
> qemu/softmmu/physmem.c:2825:23
>     #6 0x559544683662 in flatview_write qemu/softmmu/physmem.c:2867:12
>     #7 0x5595446833f3 in address_space_write qemu/softmmu/physmem.c:2963:18
>     #8 0x5595435fb082 in dma_memory_rw_relaxed 
> /home/mzy/truman/third_party/qemu/include/sysemu/dma.h:87:12
>     #9 0x5595435fb082 in dma_memory_rw 
> /home/mzy/truman/third_party/qemu/include/sysemu/dma.h:130:12
>     #10 0x5595435fb082 in dma_memory_write 
> /home/mzy/truman/third_party/qemu/include/sysemu/dma.h:171:12
>     #11 0x5595435fb082 in stl_le_dma 
> /home/mzy/truman/third_party/qemu/include/sysemu/dma.h:272:1
>     #12 0x5595435fb082 in stl_le_pci_dma 
> /home/mzy/truman/third_party/qemu/include/hw/pci/pci.h:910:1
>     #13 0x5595435fb082 in tulip_desc_write qemu/hw/net/tulip.c:101:9
>     #14 0x5595435f7e3d in tulip_xmit_list_update qemu/hw/net/tulip.c:706:9
>     #15 0x5595435f204a in tulip_write qemu/hw/net/tulip.c:805:13
>
> Fix this bug by restricting the DMA engine to memories regions.
>
> Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>

Queued for 7.2.

Thanks

> ---
>  hw/net/tulip.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/net/tulip.c b/hw/net/tulip.c
> index 097e905bec..b9e42c322a 100644
> --- a/hw/net/tulip.c
> +++ b/hw/net/tulip.c
> @@ -70,7 +70,7 @@ static const VMStateDescription vmstate_pci_tulip = {
>  static void tulip_desc_read(TULIPState *s, hwaddr p,
>          struct tulip_descriptor *desc)
>  {
> -    const MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
> +    const MemTxAttrs attrs = { .memory = true };
>
>      if (s->csr[0] & CSR0_DBO) {
>          ldl_be_pci_dma(&s->dev, p, &desc->status, attrs);
> @@ -88,7 +88,7 @@ static void tulip_desc_read(TULIPState *s, hwaddr p,
>  static void tulip_desc_write(TULIPState *s, hwaddr p,
>          struct tulip_descriptor *desc)
>  {
> -    const MemTxAttrs attrs = MEMTXATTRS_UNSPECIFIED;
> +    const MemTxAttrs attrs = { .memory = true };
>
>      if (s->csr[0] & CSR0_DBO) {
>          stl_be_pci_dma(&s->dev, p, desc->status, attrs);
> --
> 2.25.1
>