<div dir="ltr"><div class="gmail_extra">LGTM</div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jan 21, 2015 at 10:03 AM, Will Newton <span dir="ltr"><<a href="mailto:will.newton@linaro.org" target="_blank">will.newton@linaro.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Add support for checking overflow when applying a R_AARCH64_ABS32<br>
relocation and add a test to ensure it behaves correctly.<br>
---<br>
.../ELF/AArch64/AArch64RelocationHandler.cpp | 20 ++++++--<br>
test/elf/AArch64/rel-abs32-overflow.test | 53 ++++++++++++++++++++++<br>
2 files changed, 68 insertions(+), 5 deletions(-)<br>
create mode 100644 test/elf/AArch64/rel-abs32-overflow.test<br>
<br>
diff --git a/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp<br>
index 924836d..85a3038 100644<br>
--- a/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp<br>
+++ b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationHandler.cpp<br>
@@ -16,6 +16,13 @@ using namespace elf;<br>
<br>
#define PAGE(X) ((X) & ~0x0FFFL)<br>
<br>
+/// \brief Check X is in the interval (-2^(bits-1), 2^bits]<br>
+bool withinSignedUnsignedRange(int64_t X, int bits) {<br>
+ if (X < -(1L << (bits - 1)) || X >= (1L << bits))<br>
+ return false;<br>
+ return true;<br>
+}<br>
+<br>
/// \brief R_AARCH64_ABS64 - word64: S + A<br>
static void relocR_AARCH64_ABS64(uint8_t *location, uint64_t P, uint64_t S,<br>
int64_t A) {<br>
@@ -41,9 +48,11 @@ static void relocR_AARCH64_PREL32(uint8_t *location, uint64_t P, uint64_t S,<br>
}<br>
<br>
/// \brief R_AARCH64_ABS32 - word32: S + A<br>
-static void relocR_AARCH64_ABS32(uint8_t *location, uint64_t P, uint64_t S,<br>
- int64_t A) {<br>
- int32_t result = (int32_t)(S + A);<br>
+static std::error_code relocR_AARCH64_ABS32(uint8_t *location, uint64_t P,<br>
+ uint64_t S, int64_t A) {<br>
+ int64_t result = S + A;<br>
+ if (!withinSignedUnsignedRange(result, 32))<br></blockquote><div><br></div><div>Because you only pass 32 as an argument, I'd probably write (result != (int32_t)result), because it's easy to understand.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
+ return make_out_of_range_reloc_error();<br>
DEBUG_WITH_TYPE(<br>
"AArch64", llvm::dbgs() << "\t\tHandle " << LLVM_FUNCTION_NAME << " -";<br>
llvm::dbgs() << " S: 0x" << Twine::utohexstr(S);<br>
@@ -53,6 +62,7 @@ static void relocR_AARCH64_ABS32(uint8_t *location, uint64_t P, uint64_t S,<br>
*reinterpret_cast<llvm::support::ulittle32_t *>(location) =<br>
result |<br>
(int32_t) * reinterpret_cast<llvm::support::little32_t *>(location);<br>
+ return std::error_code();<br>
}<br>
<br>
/// \brief R_AARCH64_ADR_PREL_PG_HI21 - Page(S+A) - Page(P)<br>
@@ -385,8 +395,8 @@ std::error_code AArch64TargetRelocationHandler::applyRelocation(<br>
ref.addend());<br>
break;<br>
case R_AARCH64_ABS32:<br>
- relocR_AARCH64_ABS32(location, relocVAddress, targetVAddress, ref.addend());<br>
- break;<br>
+ return relocR_AARCH64_ABS32(location, relocVAddress, targetVAddress,<br>
+ ref.addend());<br>
// Runtime only relocations. Ignore here.<br>
case R_AARCH64_RELATIVE:<br>
case R_AARCH64_IRELATIVE:<br>
diff --git a/test/elf/AArch64/rel-abs32-overflow.test b/test/elf/AArch64/rel-abs32-overflow.test<br>
new file mode 100644<br>
index 0000000..be65ebc<br>
--- /dev/null<br>
+++ b/test/elf/AArch64/rel-abs32-overflow.test<br>
@@ -0,0 +1,53 @@<br>
+# Check handling of R_AARCH64_ABS32 relocation overflow.<br>
+# RUN: yaml2obj -format=elf %s > %t-obj<br>
+# RUN: not lld -flavor gnu -target arm64 -o %t-exe %t-obj 2>&1 | FileCheck %s<br>
+<br>
+# CHECK: Relocation out of range in file {{.*}}: reference from data1+0 to data2+34359738369 of type 258 (R_AARCH64_ABS32)<br>
+# CHECK: Relocation out of range in file {{.*}}: reference from data2+0 to data1+34359738369 of type 258 (R_AARCH64_ABS32)<br>
+<br>
+!ELF<br>
+FileHeader: !FileHeader<br>
+ Class: ELFCLASS64<br>
+ Data: ELFDATA2LSB<br>
+ Type: ET_REL<br>
+ Machine: EM_AARCH64<br>
+<br>
+Sections:<br>
+- Name: .text<br>
+ Type: SHT_PROGBITS<br>
+ Content: "00000000"<br>
+ AddressAlign: 16<br>
+ Flags: [SHF_ALLOC, SHF_EXECINSTR]<br>
+- Name: .data<br>
+ Type: SHT_PROGBITS<br>
+ Content: "0000000000000000"<br>
+ AddressAlign: 16<br>
+ Flags: [SHF_ALLOC, SHF_WRITE]<br>
+<br>
+- Name: .rela.data<br>
+ Type: SHT_RELA<br>
+ Info: .data<br>
+ AddressAlign: 8<br>
+ Relocations:<br>
+ - Offset: 0x0<br>
+ Symbol: data2<br>
+ Type: R_AARCH64_ABS32<br>
+ Addend: 0x800000001<br>
+ - Offset: 0x4<br>
+ Symbol: data1<br>
+ Type: R_AARCH64_ABS32<br>
+ Addend: 0x800000001<br>
+<br>
+Symbols:<br>
+ Global:<br>
+ - Name: _start<br>
+ Section: .text<br>
+ Value: 0x0<br>
+ Size: 4<br>
+ - Name: data1<br>
+ Section: .data<br>
+ Size: 4<br>
+ - Name: data2<br>
+ Section: .data<br>
+ Value: 0x4<br>
+ Size: 4<br>
<span class="HOEnZb"><font color="#888888">--<br>
2.1.0<br>
<br>
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</font></span></blockquote></div><br></div></div>