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[NTOS:KE/x64] Fix handling of non-volatiles in trap vs exception frame

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The registers that are saved/restored in the trap / exception frame need to be consistent between all entry/exit points as well as the functions that convert between trap/exception frame and context. The trap frame contains only the non-volatile registers and rbp, the rest is saved in the exception frame.
The previous code didn't save rbp in the syscall handler, which led to it being clobbered when exiting though KiServiceExit2 rather than returning back to the syscall exit path. Also KeContextToTrapFrame would use rbx, rsi and rdi from the trap frame, which wouldn't be saved there by the syscall handler.
This commit is contained in:
Timo Kreuzer 2022-12-15 21:55:16 +02:00
parent 83e741c643
commit 05456808e8
3 changed files with 6 additions and 21 deletions
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6
ntoskrnl/ke/amd64/context.c
View file

@ -36,11 +36,8 @@ KeContextToTrapFrame(IN PCONTEXT Context,
if (ContextFlags & CONTEXT_INTEGER)
{
TrapFrame->Rax = Context->Rax;
TrapFrame->Rbx = Context->Rbx;
TrapFrame->Rcx = Context->Rcx;
TrapFrame->Rdx = Context->Rdx;
TrapFrame->Rsi = Context->Rsi;
TrapFrame->Rdi = Context->Rdi;
TrapFrame->Rbp = Context->Rbp;
TrapFrame->R8 = Context->R8;
TrapFrame->R9 = Context->R9;
@ -48,6 +45,9 @@ KeContextToTrapFrame(IN PCONTEXT Context,
TrapFrame->R11 = Context->R11;
if (ExceptionFrame)
{
ExceptionFrame->Rbx = Context->Rbx;
ExceptionFrame->Rsi = Context->Rsi;
ExceptionFrame->Rdi = Context->Rdi;
ExceptionFrame->R12 = Context->R12;
ExceptionFrame->R13 = Context->R13;
ExceptionFrame->R14 = Context->R14;

4
ntoskrnl/ke/amd64/trap.S
View file

@ -781,6 +781,7 @@ PUBLIC KiSystemCallEntry64
/* The unwind info pretends we have a machine frame */
.PUSHFRAME
.ALLOCSTACK (KTRAP_FRAME_LENGTH + MAX_SYSCALL_PARAM_SIZE - MachineFrameLength)
.SAVEREG rbp, MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rbp
.ENDPROLOG
/* Swap gs to kernel, so we can access the PCR */
@ -795,7 +796,7 @@ PUBLIC KiSystemCallEntry64
/* Allocate a TRAP_FRAME and space for parameters */
sub rsp, (KTRAP_FRAME_LENGTH + MAX_SYSCALL_PARAM_SIZE)
/* Save volatile registers in the trap frame */
/* Save volatile registers and rbp in the trap frame */
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rax], rax
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rip], rcx
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rdx], rdx
@ -803,6 +804,7 @@ PUBLIC KiSystemCallEntry64
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_R9], r9
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rcx], r10
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_EFlags], r11
mov [rsp + MAX_SYSCALL_PARAM_SIZE + KTRAP_FRAME_Rbp], rbp
/* Store user stack pointer in the trap frame */
mov rax, gs:[PcUserRsp]

17
sdk/include/asm/trapamd64.inc
View file

@ -108,16 +108,6 @@ MACRO(EnterTrap, Flags)
lea rbp, [rsp]
.setframe rbp, 0
if (Flags AND TF_NONVOLATILES)
/* Save non-volatile registers */
mov [rbp + KTRAP_FRAME_Rbx], rbx
.savereg rbx, KTRAP_FRAME_Rbx
mov [rbp + KTRAP_FRAME_Rdi], rdi
.savereg rdi, KTRAP_FRAME_Rdi
mov [rbp + KTRAP_FRAME_Rsi], rsi
.savereg rsi, KTRAP_FRAME_Rsi
endif
.endprolog
if (Flags AND TF_VOLATILES)
@ -243,13 +233,6 @@ MACRO(ExitTrap, Flags)
kernel_mode_return:
if (Flags AND TF_NONVOLATILES)
/* Restore non-volatile registers */
mov rbx, [rbp + KTRAP_FRAME_Rbx]
mov rdi, [rbp + KTRAP_FRAME_Rdi]
mov rsi, [rbp + KTRAP_FRAME_Rsi]
endif
if (Flags AND TF_VOLATILES)
/* Restore volatile registers */
mov rax, [rbp + KTRAP_FRAME_Rax]