[compiler-rt] bc34a83 - [ASan][Windows] Fix rip-relative instruction replacement (#68432)
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Mon Oct 9 14:53:12 PDT 2023
Author: nicole mazzuca
Date: 2023-10-09T14:53:07-07:00
New Revision: bc34a83380152e44fdb75ff7c66ab8f1970c4633
URL: https://github.com/llvm/llvm-project/commit/bc34a83380152e44fdb75ff7c66ab8f1970c4633
DIFF: https://github.com/llvm/llvm-project/commit/bc34a83380152e44fdb75ff7c66ab8f1970c4633.diff
LOG: [ASan][Windows] Fix rip-relative instruction replacement (#68432)
The old code incorrectly checked what relative offsets were allowed.
The correct check is that the offset from the target to the instruction
pointer should be within $[-2^{31}, 2^{31})$; however, the check that
was originally written was that the offset was within $[0, 2^{31})$.
Negative offsets are certainly allowable (as long as they fit in 32
bits), and this change fixes that.
Added:
Modified:
compiler-rt/lib/interception/interception_win.cpp
Removed:
################################################################################
diff --git a/compiler-rt/lib/interception/interception_win.cpp b/compiler-rt/lib/interception/interception_win.cpp
index 23d26ea94b51a66..d57afa3fda7bcb8 100644
--- a/compiler-rt/lib/interception/interception_win.cpp
+++ b/compiler-rt/lib/interception/interception_win.cpp
@@ -726,16 +726,22 @@ static bool CopyInstructions(uptr to, uptr from, size_t size) {
size_t instruction_size = GetInstructionSize(from + cursor, &rel_offset);
if (!instruction_size)
return false;
- _memcpy((void*)(to + cursor), (void*)(from + cursor),
+ _memcpy((void *)(to + cursor), (void *)(from + cursor),
(size_t)instruction_size);
if (rel_offset) {
- uptr delta = to - from;
- uptr relocated_offset = *(u32*)(to + cursor + rel_offset) - delta;
-#if SANITIZER_WINDOWS64
- if (relocated_offset + 0x80000000U >= 0xFFFFFFFFU)
+# if SANITIZER_WINDOWS64
+ // we want to make sure that the new relative offset still fits in 32-bits
+ // this will be untrue if relocated_offset \notin [-2**31, 2**31)
+ s64 delta = to - from;
+ s64 relocated_offset = *(s32 *)(to + cursor + rel_offset) - delta;
+ if (-0x8000'0000ll > relocated_offset || relocated_offset > 0x7FFF'FFFFll)
return false;
-#endif
- *(u32*)(to + cursor + rel_offset) = relocated_offset;
+# else
+ // on 32-bit, the relative offset will always be correct
+ s32 delta = to - from;
+ s32 relocated_offset = *(s32 *)(to + cursor + rel_offset) - delta;
+# endif
+ *(s32 *)(to + cursor + rel_offset) = relocated_offset;
}
cursor += instruction_size;
}
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