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[BOLT] Gadget scanner: do not crash on debug-printing CFI instructions #136151

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[BOLT] Gadget scanner: do not crash on debug-printing CFI instructions #136151

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16 changes: 16 additions & 0 deletions bolt/lib/Passes/PAuthGadgetScanner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -430,6 +430,9 @@ class SrcSafetyAnalysis {
}

SrcState computeNext(const MCInst &Point, const SrcState &Cur) {
if (BC.MIB->isCFI(Point))
return Cur;

SrcStatePrinter P(BC);
LLVM_DEBUG({
dbgs() << " SrcSafetyAnalysis::ComputeNext(";
Expand Down Expand Up @@ -704,6 +707,8 @@ class CFGUnawareSrcSafetyAnalysis : public SrcSafetyAnalysis,
SrcState S = createEntryState();
for (auto &I : BF.instrs()) {
MCInst &Inst = I.second;
if (BC.MIB->isCFI(Inst))
continue;

// If there is a label before this instruction, it is possible that it
// can be jumped-to, thus conservatively resetting S. As an exception,
Expand Down Expand Up @@ -998,6 +1003,9 @@ class DstSafetyAnalysis {
}

DstState computeNext(const MCInst &Point, const DstState &Cur) {
if (BC.MIB->isCFI(Point))
return Cur;

DstStatePrinter P(BC);
LLVM_DEBUG({
dbgs() << " DstSafetyAnalysis::ComputeNext(";
Expand Down Expand Up @@ -1165,6 +1173,8 @@ class CFGUnawareDstSafetyAnalysis : public DstSafetyAnalysis,
DstState S = createUnsafeState();
for (auto &I : llvm::reverse(BF.instrs())) {
MCInst &Inst = I.second;
if (BC.MIB->isCFI(Inst))
continue;

// If Inst can change the control flow, we cannot be sure that the next
// instruction (to be executed in analyzed program) is the one processed
Expand Down Expand Up @@ -1355,6 +1365,9 @@ void FunctionAnalysisContext::findUnsafeUses(
});

iterateOverInstrs(BF, [&](MCInstReference Inst) {
if (BC.MIB->isCFI(Inst))
return;

const SrcState &S = Analysis->getStateBefore(Inst);

// If non-empty state was never propagated from the entry basic block
Expand Down Expand Up @@ -1418,6 +1431,9 @@ void FunctionAnalysisContext::findUnsafeDefs(
});

iterateOverInstrs(BF, [&](MCInstReference Inst) {
if (BC.MIB->isCFI(Inst))
return;

const DstState &S = Analysis->getStateAfter(Inst);

if (auto Report = shouldReportAuthOracle(BC, Inst, S))
Expand Down
32 changes: 32 additions & 0 deletions bolt/test/binary-analysis/AArch64/gs-pauth-debug-output.s
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Original file line number Diff line number Diff line change
Expand Up @@ -329,6 +329,38 @@ auth_oracle:
// PAUTH-EMPTY:
// PAUTH-NEXT: Attaching leakage info to: 00000000: autia x0, x1 # DataflowDstSafetyAnalysis: dst-state<CannotEscapeUnchecked: BitVector, Insts: [0](0x{{[0-9a-f]+}} )>

// Gadget scanner should not crash on CFI instructions, including when debug-printing them.
// Note that the particular debug output is not checked, but BOLT should be
// compiled with assertions enabled to support -debug-only argument.

.globl cfi_inst_df
.type cfi_inst_df,@function
cfi_inst_df:
.cfi_startproc
sub sp, sp, #16
.cfi_def_cfa_offset 16
add sp, sp, #16
.cfi_def_cfa_offset 0
ret
.size cfi_inst_df, .-cfi_inst_df
.cfi_endproc

.globl cfi_inst_nocfg
.type cfi_inst_nocfg,@function
cfi_inst_nocfg:
.cfi_startproc
sub sp, sp, #16
.cfi_def_cfa_offset 16

adr x0, 1f
br x0
1:
add sp, sp, #16
.cfi_def_cfa_offset 0
ret
.size cfi_inst_nocfg, .-cfi_inst_nocfg
.cfi_endproc

// CHECK-LABEL:Analyzing function main, AllocatorId = 1
.globl main
.type main,@function
Expand Down
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