userlib: Add a fallback dummy section if .bss is empty

Binaries without uninitialized global variable may generate a `.bss` LOAD segment with no valid content (`p_filesz` = 0, `p_memsz` = 0). The problem with such a segment is that ELF parser may fail with unaligned segment address error. To avoid this, add a dummy `.bss` to force non-zero memory allocation, ensuring a meaningful PT_LOAD. Signed-off-by: Vijay Dhanraj <[email protected]>
coconut-svsm · Dec 10, 2024 · 4a6fef6 · 4a6fef6
1 parent ee99ff7
commit 4a6fef6
Showing 1 changed file with 8 additions and 1 deletion.
diff --git a/user/lib/module.lds b/user/lib/module.lds
@@ -48,12 +48,19 @@ SECTIONS
 	} :rodata
 	_erodata = .;
 	. = ALIGN(4096);
-	.bss : {
+	.bss (NOLOAD) : {
 		_bss = .;
 		*(.bss) *(.bss.[0-9a-zA-Z_]*)
 		. = ALIGN(16);
 		_ebss = .;
 	} :bss
+
+	/* Fallback dummy section if `.bss` is empty */
+	. = ALIGN(4096);
+	.bss_dummy (NOLOAD) : {
+		LONG(0);
+	} :bss
+
 	. = ALIGN(4096);
 	heap_start = .;
 }