From 877ec97b75b23f564eba544213ea822359c23d17 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@well-typed.com>
Date: Tue, 14 Feb 2023 16:08:50 -0500
Subject: [PATCH] linker/PEi386: Don't sign-extend symbol section number
Previously we incorrectly interpreted PE section numbers as signed
values. However, this isn't the case; rather, it's an unsigned 16-bit number
with a few special bit-patterns (0xffff and 0xfffe). This resulted in #22941
as the linker would conclude that the sections were invalid.
Fixing this required quite a bit of refactoring.
Closes #22941.
---
rts/linker/PEi386.c | 77 +++++++++++++++++++++++++++++++++++++++------
rts/linker/PEi386.h | 2 +-
2 files changed, 68 insertions(+), 11 deletions(-)
diff --git a/rts/linker/PEi386.c b/rts/linker/PEi386.c
index e404abc85cc..05a545647a9 100644
--- a/rts/linker/PEi386.c
+++ b/rts/linker/PEi386.c
@@ -697,8 +697,16 @@ size_t getSymbolSize ( COFF_HEADER_INFO *info )
}
}
+// Constants which may be returned by getSymSectionNumber.
+// See https://learn.microsoft.com/en-us/windows/win32/debug/pe-format#section-number-values
+#define PE_SECTION_UNDEFINED ((uint32_t) 0)
+#define PE_SECTION_ABSOLUTE ((uint32_t) -1)
+#define PE_SECTION_DEBUG ((uint32_t) -2)
+
+// Returns either PE_SECTION_{UNDEFINED,ABSOLUTE,DEBUG} or the (one-based)
+// section number of the given symbol.
__attribute__ ((always_inline)) inline
-int32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym )
+uint32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym )
{
ASSERT(info);
ASSERT(sym);
@@ -707,7 +715,13 @@ int32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym )
case COFF_ANON_BIG_OBJ:
return sym->ex.SectionNumber;
default:
- return sym->og.SectionNumber;
+ // Take care to only sign-extend reserved values; see #22941.
+ switch (sym->og.SectionNumber) {
+ case IMAGE_SYM_UNDEFINED: return PE_SECTION_UNDEFINED;
+ case IMAGE_SYM_ABSOLUTE : return PE_SECTION_ABSOLUTE;
+ case IMAGE_SYM_DEBUG: return PE_SECTION_DEBUG;
+ default: return (uint16_t) sym->og.SectionNumber;
+ }
}
}
@@ -1652,7 +1666,7 @@ ocGetNames_PEi386 ( ObjectCode* oc )
StgWord globalBssSize = 0;
for (unsigned int i=0; i < info->numberOfSymbols; i++) {
COFF_symbol* sym = &oc->info->symbols[i];
- if (getSymSectionNumber (info, sym) == IMAGE_SYM_UNDEFINED
+ if (getSymSectionNumber (info, sym) == PE_SECTION_UNDEFINED
&& getSymValue (info, sym) > 0
&& getSymStorageClass (info, sym) != IMAGE_SYM_CLASS_SECTION) {
globalBssSize += getSymValue (info, sym);
@@ -1685,21 +1699,39 @@ ocGetNames_PEi386 ( ObjectCode* oc )
for (unsigned int i = 0; i < (uint32_t)oc->n_symbols; i++) {
COFF_symbol* sym = &oc->info->symbols[i];
- int32_t secNumber = getSymSectionNumber (info, sym);
uint32_t symValue = getSymValue (info, sym);
uint8_t symStorageClass = getSymStorageClass (info, sym);
-
SymbolAddr *addr = NULL;
bool isWeak = false;
SymbolName *sname = get_sym_name (getSymShortName (info, sym), oc);
- Section *section = secNumber > 0 ? &oc->sections[secNumber-1] : NULL;
+
+ uint32_t secNumber = getSymSectionNumber (info, sym);
+ Section *section;
+ switch (secNumber) {
+ case PE_SECTION_UNDEFINED:
+ // N.B. This may be a weak symbol
+ section = NULL;
+ break;
+ case PE_SECTION_ABSOLUTE:
+ IF_DEBUG(linker, debugBelch("symbol %s is ABSOLUTE, skipping...\n", sname));
+ i += getSymNumberOfAuxSymbols (info, sym);
+ continue;
+ case PE_SECTION_DEBUG:
+ IF_DEBUG(linker, debugBelch("symbol %s is DEBUG, skipping...\n", sname));
+ i += getSymNumberOfAuxSymbols (info, sym);
+ continue;
+ default:
+ CHECK(secNumber < (uint32_t) oc->n_sections);
+ section = &oc->sections[secNumber-1];
+ }
SymType type;
switch (getSymType(oc->info->ch_info, sym)) {
case 0x00: type = SYM_TYPE_DATA; break;
case 0x20: type = SYM_TYPE_CODE; break;
default:
- debugBelch("Invalid symbol type: 0x%x\n", getSymType(oc->info->ch_info, sym));
+ debugBelch("Symbol %s has invalid type 0x%x\n",
+ sname, getSymType(oc->info->ch_info, sym));
return 1;
}
@@ -1730,8 +1762,18 @@ ocGetNames_PEi386 ( ObjectCode* oc )
CHECK(symValue == 0);
COFF_symbol_aux_weak_external *aux = (COFF_symbol_aux_weak_external *) (sym+1);
COFF_symbol* targetSym = &oc->info->symbols[aux->TagIndex];
- int32_t targetSecNumber = getSymSectionNumber (info, targetSym);
- Section *targetSection = targetSecNumber > 0 ? &oc->sections[targetSecNumber-1] : NULL;
+
+ uint32_t targetSecNumber = getSymSectionNumber (info, targetSym);
+ Section *targetSection;
+ switch (targetSecNumber) {
+ case PE_SECTION_UNDEFINED:
+ case PE_SECTION_ABSOLUTE:
+ case PE_SECTION_DEBUG:
+ targetSection = NULL;
+ break;
+ default:
+ targetSection = &oc->sections[targetSecNumber-1];
+ }
addr = (SymbolAddr*) ((size_t) targetSection->start + getSymValue(info, targetSym));
}
else if ( secNumber == IMAGE_SYM_UNDEFINED && symValue > 0) {
@@ -1850,6 +1892,9 @@ ocGetNames_PEi386 ( ObjectCode* oc )
return false;
break;
+ } else if (secNumber == PE_SECTION_UNDEFINED) {
+ IF_DEBUG(linker, debugBelch("symbol %s is UNDEFINED, skipping...\n", sname));
+ i += getSymNumberOfAuxSymbols (info, sym);
}
if ((addr != NULL || isWeak)
@@ -1976,7 +2021,19 @@ ocResolve_PEi386 ( ObjectCode* oc )
debugBelch("'\n" ));
if (getSymStorageClass (info, sym) == IMAGE_SYM_CLASS_STATIC) {
- Section section = oc->sections[getSymSectionNumber (info, sym)-1];
+ uint32_t sect_n = getSymSectionNumber (info, sym);
+ switch (sect_n) {
+ case PE_SECTION_UNDEFINED:
+ case PE_SECTION_ABSOLUTE:
+ case PE_SECTION_DEBUG:
+ errorBelch(" | %" PATH_FMT ": symbol `%s' has invalid section number %02x",
+ oc->fileName, symbol, sect_n);
+ return false;
+ default:
+ break;
+ }
+ CHECK(sect_n < (uint32_t) oc->n_sections);
+ Section section = oc->sections[sect_n - 1];
S = ((size_t)(section.start))
+ ((size_t)(getSymValue (info, sym)));
} else {
diff --git a/rts/linker/PEi386.h b/rts/linker/PEi386.h
index 6bb15256c92..a3b05e30cb4 100644
--- a/rts/linker/PEi386.h
+++ b/rts/linker/PEi386.h
@@ -143,7 +143,7 @@ struct _Alignments {
COFF_OBJ_TYPE getObjectType ( char* image, pathchar* fileName );
COFF_HEADER_INFO* getHeaderInfo ( ObjectCode* oc );
size_t getSymbolSize ( COFF_HEADER_INFO *info );
-int32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym );
+uint32_t getSymSectionNumber ( COFF_HEADER_INFO *info, COFF_symbol* sym );
uint32_t getSymValue ( COFF_HEADER_INFO *info, COFF_symbol* sym );
uint8_t getSymStorageClass ( COFF_HEADER_INFO *info, COFF_symbol* sym );
uint8_t getSymNumberOfAuxSymbols ( COFF_HEADER_INFO *info, COFF_symbol* sym );
--
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