kbuild: remove stale *.symversions

cmd_update_lto_symversions merges all the existing *.symversions, but some of them might be stale. If the last EXPORT_SYMBOL is removed from a C file, the *.symversions file is not deleted or updated. It contains stale CRCs, but still they will be used for linking the vmlinux or modules. It is not a big deal when the EXPORT_SYMBOL is really removed. However, when the EXPORT_SYMBOL is moved to another file, the same __crc_<symbol> will appear twice in the merged *.symversions, possibly with different CRCs if the function argument is changed at the same time. It would confuse module versioning. If no EXPORT_SYMBOL is found, let's remove *.symversions explicitly. Signed-off-by: Masahiro Yamada <[email protected]> Reviewed-by: Kees Cook <[email protected]>
josf · Sep 2, 2021 · a8390ba · a8390ba
1 parent f01ac2a
commit a8390ba
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
@@ -177,6 +177,8 @@ cmd_modversions_c =								\
 	if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then			\
 		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
 		    > [email protected];						\
+	else									\
+		rm -f [email protected];						\
 	fi;
 else
 cmd_modversions_c =								\