[LLD] [COFF] Fix crashes for cfguard with undefined weak symbols (#79063)
When marking symbols as having their address taken, we can have the
sitaution where we have the address taken of a weak symbol. If there's
no strong definition of the symbol, the symbol ends up as an absolute
symbol with the value null. In those cases, we don't have any Chunk.
Skip such symbols from the cfguard tables.
This fixes https://github.com/llvm/llvm-project/issues/78619.
GitOrigin-RevId: 50d33c62ad8786400a712b01150f6decaf070782
diff --git a/COFF/Writer.cpp b/COFF/Writer.cpp
index 2e34a6c..9c20bbb 100644
--- a/COFF/Writer.cpp
+++ b/COFF/Writer.cpp
@@ -1802,6 +1802,8 @@
// symbol's offset into that Chunk.
static void addSymbolToRVASet(SymbolRVASet &rvaSet, Defined *s) {
Chunk *c = s->getChunk();
+ if (!c)
+ return;
if (auto *sc = dyn_cast<SectionChunk>(c))
c = sc->repl; // Look through ICF replacement.
uint32_t off = s->getRVA() - (c ? c->getRVA() : 0);
diff --git a/test/COFF/cfguard-weak-undef.s b/test/COFF/cfguard-weak-undef.s
new file mode 100644
index 0000000..fd4121a
--- /dev/null
+++ b/test/COFF/cfguard-weak-undef.s
@@ -0,0 +1,27 @@
+# REQUIRES: x86
+# RUN: llvm-mc -triple=x86_64-windows-gnu -filetype=obj -o %t.obj %s
+# RUN: lld-link %t.obj /out:%t.exe /entry:entry /subsystem:console /guard:cf
+
+ .def @feat.00;
+ .scl 3;
+ .type 0;
+ .endef
+ .globl @feat.00
+.set @feat.00, 2048
+
+ .globl entry
+entry:
+ retq
+
+ .data
+ .globl funcs
+funcs:
+ .quad weakfunc
+
+ .section .gfids$y,"dr"
+ .symidx weakfunc
+ .section .giats$y,"dr"
+ .section .gljmp$y,"dr"
+ .weak weakfunc
+ .addrsig
+ .addrsig_sym weakfunc
