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Commit cb7b6b1c authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

exec: cleanup the CONFIG_MODULES logic 



search_binary_handler() uses "for (try=0; try<2; try++)" to avoid "goto"
but the code looks too complicated and horrible imho.  We still need to
check "try == 0" before request_module() and add the additional "break"
for !CONFIG_MODULES case.

Kill this loop and use a simple "bool need_retry" + "goto retry".  The
code looks much simpler and we do not even need ifdef's, gcc can optimize
out the "if (need_retry)" block if !IS_ENABLED().

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Zach Levis <zml@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 92eaa565

fs/exec.c

+31 −37
Original line number Diff line number Diff line
@@ -1367,13 +1367,15 @@ int remove_arg_zero(struct linux_binprm *bprm) 
}

EXPORT_SYMBOL(remove_arg_zero);



#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))

/*

 * cycle the list of binary formats handler, until one recognizes the image

 */

int search_binary_handler(struct linux_binprm *bprm)

{

	int try, retval;

	bool need_retry = IS_ENABLED(CONFIG_MODULES);

	struct linux_binfmt *fmt;

	int retval;



	/* This allows 4 levels of binfmt rewrites before failing hard. */

	if (bprm->recursion_depth > 5)
@@ -1388,7 +1390,7 @@ int search_binary_handler(struct linux_binprm *bprm) 
		return retval;



	retval = -ENOENT;

	for (try=0; try<2; try++) {

 retry:

	read_lock(&binfmt_lock);

	list_for_each_entry(fmt, &formats, lh) {

		if (!try_module_get(fmt->module))
@@ -1411,24 +1413,16 @@ int search_binary_handler(struct linux_binprm *bprm) 
		}

	}

	read_unlock(&binfmt_lock);

#ifdef CONFIG_MODULES

		if (retval != -ENOEXEC || bprm->mm == NULL) {

			break;

		} else {

#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))

			if (printable(bprm->buf[0]) &&

			    printable(bprm->buf[1]) &&

			    printable(bprm->buf[2]) &&

			    printable(bprm->buf[3]))

				break; /* -ENOEXEC */

			if (try)

				break; /* -ENOEXEC */

			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));

		}

#else

		break;

#endif



	if (need_retry && retval == -ENOEXEC && bprm->mm) {

		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&

		    printable(bprm->buf[2]) && printable(bprm->buf[3]))

			return retval;

		request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2));

		need_retry = false;

		goto retry;

	}



	return retval;

}

EXPORT_SYMBOL(search_binary_handler);