execve updates for v6.9-rc1

- Drop needless error path code in remove_arg_zero() (Li kunyu, Kees Cook)
 
 - binfmt_elf_efpic: Don't use missing interpreter's properties (Max Filippov)
 
 - Use /bin/bash for execveat selftests
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Merge tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Drop needless error path code in remove_arg_zero() (Li kunyu, Kees
   Cook)

 - binfmt_elf_efpic: Don't use missing interpreter's properties (Max
   Filippov)

 - Use /bin/bash for execveat selftests

* tag 'execve-v6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Simplify remove_arg_zero() error path
  selftests/exec: Perform script checks with /bin/bash
  exec: Delete unnecessary statements in remove_arg_zero()
  fs: binfmt_elf_efpic: don't use missing interpreter's properties

fs/binfmt_elf_fdpic.c

@@ -320,7 +320,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
 	else
 		executable_stack = EXSTACK_DEFAULT;
 
-	if (stack_size == 0) {
+	if (stack_size == 0 && interp_params.flags & ELF_FDPIC_FLAG_PRESENT) {
 		stack_size = interp_params.stack_size;
 		if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
 			executable_stack = EXSTACK_ENABLE_X;

fs/exec.c

@@ -1719,7 +1719,6 @@ static int prepare_binprm(struct linux_binprm *bprm)
  */
 int remove_arg_zero(struct linux_binprm *bprm)
 {
-	int ret = 0;
 	unsigned long offset;
 	char *kaddr;
 	struct page *page;
@@ -1730,10 +1729,8 @@ int remove_arg_zero(struct linux_binprm *bprm)
 	do {
 		offset = bprm->p & ~PAGE_MASK;
 		page = get_arg_page(bprm, bprm->p, 0);
-		if (!page) {
-			ret = -EFAULT;
-			goto out;
-		}
+		if (!page)
+			return -EFAULT;
 		kaddr = kmap_local_page(page);
 
 		for (; offset < PAGE_SIZE && kaddr[offset];
@@ -1746,10 +1743,8 @@ int remove_arg_zero(struct linux_binprm *bprm)
 
 	bprm->p++;
 	bprm->argc--;
-	ret = 0;
 
-out:
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(remove_arg_zero);
 

tools/testing/selftests/exec/execveat.c

@@ -393,7 +393,7 @@ static int run_tests(void)
 static void prerequisites(void)
 {
 	int fd;
-	const char *script = "#!/bin/sh\nexit $*\n";
+	const char *script = "#!/bin/bash\nexit $*\n";
 
 	/* Create ephemeral copies of files */
 	exe_cp("execveat", "execveat.ephemeral");