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boundary check for CBZ/CBNZ fixup #548

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boundary check for CBZ/CBNZ fixup #548

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66a3e5c
boundary check for CBZ/CBNZ fixup
covanam Feb 17, 2023
a668d8e
return error if llvm fails
covanam May 11, 2023
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2 changes: 2 additions & 0 deletions llvm/keystone/ks.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -671,6 +671,8 @@ int ks_asm(ks_engine *ks,

if (ks->errnum >= KS_ERR_ASM)
return -1;
else if (Ctx.hadError())
return -1;
else {
*insn_size = Msg.size();
encoding = (unsigned char *)malloc(*insn_size);
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9 changes: 9 additions & 0 deletions llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
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Expand Up @@ -566,6 +566,15 @@ unsigned ARMAsmBackend::adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
// Offset by 4, and don't encode the low two bits.
return ((Value - 4) >> 2) & 0xff;
case ARM::fixup_arm_thumb_cb: {
// CB instructions can only branch to offsets in [4, 126] in multiples of 2
// so ensure that the raw value LSB is zero and it lies in [2, 130].
// An offset of 2 will be relaxed to a NOP.
if (Ctx) {
if ((int64_t)Value < 2 || Value > 0x82 || Value & 1) {
Ctx->reportError(Fixup.getLoc(), "out of range pc-relative fixup value");
return 0;
}
}
// Offset by 4 and don't encode the lower bit, which is always 0.
// FIXME: diagnose if no Thumb2
uint32_t Binary = (Value - 4) >> 1;
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