On 08/08/19 08:33, P J P wrote:
> From: Prasad J Pandit <p...@fedoraproject.org>
>
> When executing script in lsi_execute_script(), the LSI scsi
> adapter emulator advances 's->dsp' index to read next opcode.
> This can lead to an infinite loop if the next opcode is empty.
> Exit such loop after reading 10k empty opcodes.
>
> Reported-by: Bugs SysSec <bugs-sys...@rub.de>
> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
> ---
> hw/scsi/lsi53c895a.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/hw/scsi/lsi53c895a.c b/hw/scsi/lsi53c895a.c
> index 10468c1ec1..c23a40525e 100644
> --- a/hw/scsi/lsi53c895a.c
> +++ b/hw/scsi/lsi53c895a.c
> @@ -1132,7 +1132,10 @@ static void lsi_execute_script(LSIState *s)
>
> s->istat1 |= LSI_ISTAT1_SRUN;
> again:
> - insn_processed++;
> + if (++insn_processed > 10000) {
> + s->waiting = LSI_NOWAIT;
> + goto exitloop;
> + }
> insn = read_dword(s, s->dsp);
> if (!insn) {
> /* If we receive an empty opcode increment the DSP by 4 bytes
> @@ -1569,6 +1572,7 @@ again:
> }
> }
> }
> +exitloop:
> if (insn_processed > 10000 && s->waiting == LSI_NOWAIT) {
> /* Some windows drivers make the device spin waiting for a memory
> location to change. If we have been executed a lot of code then
>
I am not sure this is worth a CVE. The kernel can cause QEMU to break,
but is there a practical case in which an unprivileged user can do that?
Paolo
