View Single Post
  #9  
Old 01-05-2022, 20:46
DavidXanatos DavidXanatos is offline
Family
 
Join Date: Jun 2018
Posts: 169
Rept. Given: 2
Rept. Rcvd 41 Times in 28 Posts
Thanks Given: 54
Thanks Rcvd at 317 Times in 107 Posts
DavidXanatos Reputation: 41
I have found the solution, I needed to add the FRAME, .allocstack and .endprolog

So in the end it was some sort of alignment issue or the compile puts some additional data some ware else that were relevant.

Code:
; NTSTATUS Sbie_InvokeSyscall_asm(void* func, ULONG count, void* args);
Sbie_InvokeSyscall_asm PROC FRAME

     ; prolog
     push        rsi
     .allocstack 8
     push        rdi
     .allocstack 8
     sub         rsp, 98h ; 8 * 19 - prepare enough stack for up to 19 arguments
     .allocstack 98h
     .endprolog
     
     ; quick sanity check
     cmp         rdx, 13h ; if count > 19
     jle         arg_count_ok
     mov         rax, 0C000001Ch ; return STATUS_INVALID_SYSTEM_SERVICE
     jmp         func_return
arg_count_ok:

     ; save our 3 relevant arguments to spare registers
     mov         r11, r8  ; args
     mov         r10, rdx ; count
     mov         rax, rcx ; func

     ; check if we have higher arguments and if not skip 
     cmp         r10, 4
     jle         copy_reg_args
     ; copy arguments 5-19
     mov         rsi, r11 ; source
     add         rsi, 20h
     mov         rdi, rsp ; destination
     add         rdi, 20h
     mov         rcx, r10 ; arg count
     sub         rcx, 4   ; skip the register passed args
     rep movsq

copy_reg_args:
     ; copy arguments 1-4
     mov         r9,  qword ptr [r11+18h]
     mov         r8,  qword ptr [r11+10h]
     mov         rdx, qword ptr [r11+08h]
     mov         rcx, qword ptr [r11+00h]

     ; call the function
     call        rax

func_return:
     ; epilog
     add         rsp, 98h  
     pop         rdi
     pop         rsi

     ret  

Sbie_InvokeSyscall_asm ENDP
Reply With Quote
The Following User Says Thank You to DavidXanatos For This Useful Post:
niculaita (01-06-2022)