Commit 11c2adcd authored by Josh Poimboeuf's avatar Josh Poimboeuf
Browse files

objtool/klp: Avoid NULL pointer dereference when printing code symbol name 



Fix a hypothetical NULL pointer defereference of the 'code_sym'
variable.  In theory this should never happen.

Reviewed-and-tested-by: default avatarSong Liu <song@kernel.org>
Link: https://patch.msgid.link/64116517bc93851a98fe366ea0a4d807f4c70aab.1770759954.git.jpoimboe@kernel.org


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent e476bb27

tools/objtool/klp-diff.c

+9 −6
Original line number Diff line number Diff line
@@ -1352,7 +1352,7 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym 
{

	bool static_branch = !strcmp(sym->sec->name, "__jump_table");

	bool static_call   = !strcmp(sym->sec->name, ".static_call_sites");

	struct symbol *code_sym = NULL;

	const char *code_sym = NULL;

	unsigned long code_offset = 0;

	struct reloc *reloc;

	int ret = 0;
@@ -1372,7 +1372,7 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym 


			/* Save code location which can be printed below */

			if (reloc->sym->type == STT_FUNC && !code_sym) {

				code_sym = reloc->sym;

				code_sym = reloc->sym->name;

				code_offset = reloc_addend(reloc);

			}
@@ -1395,23 +1395,26 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym 
		if (!strcmp(sym_modname, "vmlinux"))

			continue;



		if (!code_sym)

			code_sym = "<unknown>";



		if (static_branch) {

			if (strstarts(reloc->sym->name, "__tracepoint_")) {

				WARN("%s: disabling unsupported tracepoint %s",

				     code_sym->name, reloc->sym->name + 13);

				     code_sym, reloc->sym->name + 13);

				ret = 1;

				continue;

			}



			if (strstr(reloc->sym->name, "__UNIQUE_ID_ddebug_")) {

				WARN("%s: disabling unsupported pr_debug()",

				     code_sym->name);

				     code_sym);

				ret = 1;

				continue;

			}



			ERROR("%s+0x%lx: unsupported static branch key %s.  Use static_key_enabled() instead",

			      code_sym->name, code_offset, reloc->sym->name);

			      code_sym, code_offset, reloc->sym->name);

			return -1;

		}
@@ -1422,7 +1425,7 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym 
		}



		ERROR("%s()+0x%lx: unsupported static call key %s.  Use KLP_STATIC_CALL() instead",

		      code_sym->name, code_offset, reloc->sym->name);

		      code_sym, code_offset, reloc->sym->name);

		return -1;

	}