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checkasm: aarch64: Check for stack overflows 

Also fill x8-x17 with garbage before calling the function.

Figure out the number of stack parameters and make sure that the
value on the stack after those is untouched.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Martin Storsjö 2020-05-13 14:11:39 +03:00
parent 6cb2d4d94b
commit ed7d73355e
2 changed files with 49 additions and 5 deletions
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47
tests/checkasm/aarch64/checkasm.S
View File

@ -44,8 +44,10 @@ const register_init, align=4
endconst
const error_message
const error_message_register
.asciz "failed to preserve register"
error_message_stack:
.asciz "stack clobbered"
endconst
@ -65,7 +67,8 @@ function checkasm_stack_clobber, export=1
ret
endfunc
#define ARG_STACK ((8*(MAX_ARGS - 8) + 15) & ~15)
// + 16 for stack canary reference
#define ARG_STACK ((8*(MAX_ARGS - 8) + 15) & ~15 + 16)
function checkasm_checked_call, export=1
stp x29, x30, [sp, #-16]!
@ -100,14 +103,48 @@ function checkasm_checked_call, export=1
.equ pos, pos + 8
.endr
// Fill x8-x17 with garbage. This doesn't have to be preserved,
// but avoids relying on them having any particular value.
movrel x9, register_init
ldp x10, x11, [x9], #32
ldp x12, x13, [x9], #32
ldp x14, x15, [x9], #32
ldp x16, x17, [x9], #32
ldp x8, x9, [x9]
// For stack overflows, the callee is free to overwrite the parameters
// that were passed on the stack (if any), so we can only check after
// that point. First figure out how many parameters the function
// really took on the stack:
ldr w2, [x29, #16 + 8*8 + (MAX_ARGS-8)*8]
// Load the first non-parameter value from the stack, that should be
// left untouched by the function. Store a copy of it inverted, so that
// e.g. overwriting everything with zero would be noticed.
ldr x2, [sp, x2, lsl #3]
mvn x2, x2
str x2, [sp, #ARG_STACK-8]
// Load the in-register arguments
mov x12, x0
ldp x0, x1, [x29, #16]
ldp x2, x3, [x29, #32]
ldp x4, x5, [x29, #48]
ldp x6, x7, [x29, #64]
// Call the target function
blr x12
// Load the number of stack parameters, stack canary and its reference
ldr w2, [x29, #16 + 8*8 + (MAX_ARGS-8)*8]
ldr x2, [sp, x2, lsl #3]
ldr x3, [sp, #ARG_STACK-8]
add sp, sp, #ARG_STACK
stp x0, x1, [sp, #-16]!
mvn x3, x3
cmp x2, x3
b.ne 2f
movrel x9, register_init
movi v3.8h, #0
@ -139,7 +176,11 @@ function checkasm_checked_call, export=1
cbz x3, 0f
movrel x0, error_message
movrel x0, error_message_register
b 1f
2:
movrel x0, error_message_stack
1:
bl X(checkasm_fail_func)
0:
ldp x0, x1, [sp], #16

7
tests/checkasm/checkasm.h
View File

@ -184,12 +184,15 @@ extern void (*checkasm_checked_call)(void *func, int dummy, ...);
#elif ARCH_AARCH64 && !defined(__APPLE__)
void checkasm_stack_clobber(uint64_t clobber, ...);
void checkasm_checked_call(void *func, ...);
#define declare_new(ret, ...) ret (*checked_call)(void *, int, int, int, int, int, int, int, __VA_ARGS__)\
#define declare_new(ret, ...) ret (*checked_call)(void *, int, int, int, int, int, int, int, __VA_ARGS__,\
int, int, int, int, int, int, int, int,\
int, int, int, int, int, int, int)\
= (void *)checkasm_checked_call;
#define CLOB (UINT64_C(0xdeadbeefdeadbeef))
#define call_new(...) (checkasm_stack_clobber(CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,\
CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB,CLOB),\
checked_call(func_new, 0, 0, 0, 0, 0, 0, 0, __VA_ARGS__))
checked_call(func_new, 0, 0, 0, 0, 0, 0, 0, __VA_ARGS__,\
7, 6, 5, 4, 3, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0))
#else
#define declare_new(ret, ...)
#define declare_new_float(ret, ...)