Re: [PATCH v2 1/6] hw/sd: sdhci: Don't transfer any data when command time out

[Bin Meng]

Hi Philippe,

On Fri, Feb 19, 2021 at 12:25 AM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> On 2/16/21 4:46 AM, Bin Meng wrote:
> > At the end of sdhci_send_command(), it starts a data transfer if the
> > command register indicates data is associated. But the data transfer
> > should only be initiated when the command execution has succeeded.
> >
> > With this fix, the following reproducer:
> >
> > outl 0xcf8 0x80001810
> > outl 0xcfc 0xe1068000
> > outl 0xcf8 0x80001804
> > outw 0xcfc 0x7
> > write 0xe106802c 0x1 0x0f
> > write 0xe1068004 0xc 0x2801d10101fffffbff28a384
> > write 0xe106800c 0x1f 
> > 0x9dacbbcad9e8f7061524334251606f7e8d9cabbac9d8e7f60514233241505f
> > write 0xe1068003 0x28 
> > 0x80d000251480d000252280d000253080d000253e80d000254c80d000255a80d000256880d0002576
> > write 0xe1068003 0x1 0xfe
> >
> > cannot be reproduced with the following QEMU command line:
> >
> > $ qemu-system-x86_64 -nographic -M pc-q35-5.0 \
> >       -device sdhci-pci,sd-spec-version=3 \
> >       -drive if=sd,index=0,file=null-co://,format=raw,id=mydrive \
> >       -device sd-card,drive=mydrive \
> >       -monitor none -serial none -qtest stdio
>
> Can you directly add the reproducer in tests/qtest/fuzz-sdhci-test.c
> instead, similarly to tests/qtest/fuzz-test.c?
>
> > Cc: qemu-stable@nongnu.org
> > Fixes: CVE-2020-17380
> > Fixes: CVE-2020-25085
> > Fixes: CVE-2021-3409
> > Fixes: d7dfca0807a0 ("hw/sdhci: introduce standard SD host controller")
> > Reported-by: Alexander Bulekov <alxndr@bu.edu>
> > Reported-by: Cornelius Aschermann (Ruhr-University Bochum)
> > Reported-by: Muhammad Ramdhan
> > Reported-by: Sergej Schumilo (Ruhr-University Bochum)
> > Reported-by: Simon Wrner (Ruhr-University Bochum)
> > Buglink: https://bugs.launchpad.net/qemu/+bug/1892960
> > Buglink: https://bugs.launchpad.net/qemu/+bug/1909418
> > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1928146
> > Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> > Acked-by: Alistair Francis <alistair.francis@wdc.com>
> > Tested-by: Alexander Bulekov <alxndr@bu.edu>
> > Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > ---
> >
> > (no changes since v1)
> >
> >  hw/sd/sdhci.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
> > index 8ffa539..1c5ab26 100644
> > --- a/hw/sd/sdhci.c
> > +++ b/hw/sd/sdhci.c
> > @@ -326,6 +326,7 @@ static void sdhci_send_command(SDHCIState *s)
> >      SDRequest request;
> >      uint8_t response[16];
> >      int rlen;
> > +    bool timeout = false;
> >
> >      s->errintsts = 0;
> >      s->acmd12errsts = 0;
> > @@ -349,6 +350,7 @@ static void sdhci_send_command(SDHCIState *s)
> >              trace_sdhci_response16(s->rspreg[3], s->rspreg[2],
> >                                     s->rspreg[1], s->rspreg[0]);
> >          } else {
> > +            timeout = true;
> >              trace_sdhci_error("timeout waiting for command response");
> >              if (s->errintstsen & SDHC_EISEN_CMDTIMEOUT) {
> >                  s->errintsts |= SDHC_EIS_CMDTIMEOUT;
> > @@ -369,7 +371,7 @@ static void sdhci_send_command(SDHCIState *s)
> >
> >      sdhci_update_irq(s);
> >
> > -    if (s->blksize && (s->cmdreg & SDHC_CMD_DATA_PRESENT)) {
> > +    if (!timeout && s->blksize && (s->cmdreg & SDHC_CMD_DATA_PRESENT)) {
>
> No need to add 'timeout':

But s->errintsts only gets updated if (s->errintstsen & SDHC_EISEN_CMDTIMEOUT).

>
>        if ((s->errintsts & SDHC_EIS_CMDTIMEOUT)
>                && s->blksize
>                && (s->cmdreg & SDHC_CMD_DATA_PRESENT)) {
>
> >          s->data_count = 0;
> >          sdhci_data_transfer(s);
> >      }

Regards,
Bin