[llvm] 94382c8 - [llvm][StackProtector] Add noreturn to __stack_chk_fail call (#143976)

[Leonard Chan via llvm-commits]

Author: Leonard Chan
Date: 2025-07-16T13:12:28-07:00
New Revision: 94382c8e56e878d1b6a8cf317e3632df5352e23e

URL: https://github.com/llvm/llvm-project/commit/94382c8e56e878d1b6a8cf317e3632df5352e23e
DIFF: https://github.com/llvm/llvm-project/commit/94382c8e56e878d1b6a8cf317e3632df5352e23e.diff

LOG: [llvm][StackProtector] Add noreturn to __stack_chk_fail call (#143976)

This is a reland for 99e53cb4139eda491f97cb33ee42ea424d352200 with the
appropriate test fixes.

It's possible for __stack_chk_fail to be an alias when using CrossDSOCFI
since it will make a jump table entry for this function and replace it
with an alias. StackProtector can crash since it always expects this to
be a regular function. Instead add the noreturn attribute to the call.

Added: 
    llvm/test/Transforms/StackProtector/cross-dso-cfi-stack-chk-fail.ll
    llvm/test/Transforms/StackProtector/stack-chk-fail-alias.ll

Modified: 
    llvm/lib/CodeGen/StackProtector.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
index 9cc9af88c5e4f..b79911bcf3c49 100644
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/lib/CodeGen/StackProtector.cpp
@@ -731,8 +731,8 @@ BasicBlock *CreateFailBB(Function *F, const TargetLowering &TLI) {
   }
 
   if (StackChkFail) {
-    cast<Function>(StackChkFail.getCallee())->addFnAttr(Attribute::NoReturn);
-    B.CreateCall(StackChkFail, Args);
+    CallInst *Call = B.CreateCall(StackChkFail, Args);
+    Call->addFnAttr(Attribute::NoReturn);
   }
 
   B.CreateUnreachable();

diff  --git a/llvm/test/Transforms/StackProtector/cross-dso-cfi-stack-chk-fail.ll b/llvm/test/Transforms/StackProtector/cross-dso-cfi-stack-chk-fail.ll
new file mode 100644
index 0000000000000..9a102768b1277
--- /dev/null
+++ b/llvm/test/Transforms/StackProtector/cross-dso-cfi-stack-chk-fail.ll
@@ -0,0 +1,34 @@
+;; This is a minimal reproducer that caused StackProtector to crash with a bad cast when
+;; CrossDSOCFI is used. This test just needs to not crash.
+; REQUIRES: x86-registered-target
+; RUN: opt -mtriple=x86_64-pc-linux-gnu %s -passes=lowertypetests,cross-dso-cfi,stack-protector
+
+define hidden void @__stack_chk_fail() !type !1{
+  unreachable
+}
+
+define void @store_captures() sspstrong {
+entry:
+  %a = alloca i32, align 4
+  %j = alloca ptr, align 8
+  store ptr %a, ptr %j, align 8
+  ret void
+}
+
+define void @func(ptr %0) {
+entry:
+  %1 = call i1 @llvm.type.test(ptr %0, metadata !"typeid")
+  br i1 %1, label %cont, label %trap
+
+trap:                                             ; preds = %entry
+  call void @llvm.trap()
+  unreachable
+
+cont:                                             ; preds = %entry
+  call void %0()
+  ret void
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 4, !"Cross-DSO CFI", i32 1}
+!1 = !{i64 0, !"typeid"}

diff  --git a/llvm/test/Transforms/StackProtector/stack-chk-fail-alias.ll b/llvm/test/Transforms/StackProtector/stack-chk-fail-alias.ll
new file mode 100644
index 0000000000000..def3e014797de
--- /dev/null
+++ b/llvm/test/Transforms/StackProtector/stack-chk-fail-alias.ll
@@ -0,0 +1,22 @@
+;; __stack_chk_fail should have the noreturn attr even if it is an alias
+; REQUIRES: x86-registered-target
+; RUN: opt -mtriple=x86_64-pc-linux-gnu %s -passes=stack-protector -S | FileCheck %s
+
+define hidden void @__stack_chk_fail_impl() {
+  unreachable
+}
+
+ at __stack_chk_fail = hidden alias void (), ptr @__stack_chk_fail_impl
+
+; CHECK-LABEL: @store_captures(
+; CHECK:       CallStackCheckFailBlk:
+; CHECK-NEXT:      call void @__stack_chk_fail() [[ATTRS:#.*]]
+define void @store_captures() sspstrong {
+entry:
+  %a = alloca i32, align 4
+  %j = alloca ptr, align 8
+  store ptr %a, ptr %j, align 8
+  ret void
+}
+
+; CHECK: attributes [[ATTRS]] = { noreturn }