The DxgkDdiEscape handler for 0x100008b accepts a user supplied size as the
limit for a loop, leading to OOB reads and writes.
The supplied PoC passes an invalid size of 0x41414141, which causes a crash in:
__int64 sub_30A500(__int64 a1, __int64 a2, _DWORD *ptr, unsigned int user_supplied_size)
{
__int64 i; // r11@2
if ( user_supplied_size )
{
i = user_supplied_size;
do
{
if ( *ptr == 3 || (unsigned int)(*ptr - 9) <= 1 )
*ptr = 0;
ptr += 3;
--i;
}
while ( i );
Crashing context on Win 10 x64, driver version 375.70:
TRAP_FRAME: ffffd000266219e0 -- (.trap 0xffffd000266219e0)
NOTE: The trap frame does not contain all registers.
Some register values may be zeroed or incorrect.
rax=00000000fffffff7 rbx=0000000000000000 rcx=ffffe000d6315000
rdx=ffffe000d691b000 rsi=0000000000000000 rdi=0000000000000000
rip=fffff8010e34a50b rsp=ffffd00026621b78 rbp=ffffe000d691b000
r8=ffffd000266228a8 r9=0000000041414141 r10=ffffd00026623004
r11=00000000414140a4 r12=0000000000000000 r13=0000000000000000
r14=0000000000000000 r15=0000000000000000
iopl=0 nv up ei pl nz na pe nc
nvlddmkm+0x2fa50b:
fffff801`0e34a50b 418b02 mov eax,dword ptr [r10] ds:ffffd000`26623004=????????
This bug is subject to a 90 day disclosure deadline. If 90 days elapse
without a broadly available patch, then the bug report will automatically
become visible to the public.
