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Commit 91e37a79 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

module: don't ignore vermagic string if module doesn't have modversions 



Linus found a logic bug: we ignore the version number in a module's
vermagic string if we have CONFIG_MODVERSIONS set, but modversions
also lets through a module with no __versions section for modprobe
--force (with tainting, but still).

We should only ignore the start of the vermagic string if the module
actually *has* crcs to check.  Rather than (say) having an
entertaining hissy fit and creating a config option to work around the
buggy code.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a5dd6970

init/Kconfig

+3 −3
Original line number Diff line number Diff line
@@ -845,9 +845,9 @@ config MODULE_FORCE_LOAD 
	depends on MODULES

	default n

	help

	  This option allows loading of modules even if that would set the

          'F' (forced) taint, due to lack of version info.  Which is

	  usually a really bad idea.

	  Allow loading of modules without version information (ie. modprobe

	  --force).  Forced module loading sets the 'F' (forced) taint flag and

	  is usually a really bad idea.



config MODULE_UNLOAD

	bool "Module unloading"

kernel/module.c

+10 −6
Original line number Diff line number Diff line
@@ -957,11 +957,14 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs, 
	return check_version(sechdrs, versindex, "struct_module", mod, crc);

}



/* First part is kernel version, which we ignore. */

static inline int same_magic(const char *amagic, const char *bmagic)

/* First part is kernel version, which we ignore if module has crcs. */

static inline int same_magic(const char *amagic, const char *bmagic,

			     bool has_crcs)

{

	if (has_crcs) {

		amagic += strcspn(amagic, " ");

		bmagic += strcspn(bmagic, " ");

	}

	return strcmp(amagic, bmagic) == 0;

}

#else
@@ -981,7 +984,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs, 
	return 1;

}



static inline int same_magic(const char *amagic, const char *bmagic)

static inline int same_magic(const char *amagic, const char *bmagic,

			     bool has_crcs)

{

	return strcmp(amagic, bmagic) == 0;

}
@@ -1874,7 +1878,7 @@ static struct module *load_module(void __user *umod, 
		err = try_to_force_load(mod, "magic");

		if (err)

			goto free_hdr;

	} else if (!same_magic(modmagic, vermagic)) {

	} else if (!same_magic(modmagic, vermagic, versindex)) {

		printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",

		       mod->name, modmagic, vermagic);

		err = -ENOEXEC;