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: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/init/Kconfig b/init/Kconfig
index 3b5adbf..6135d07 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -845,9 +845,9 @@
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"
diff --git a/kernel/module.c b/kernel/module.c
index 2584c0e..f5e9491 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -957,11 +957,14 @@
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)
{
- amagic += strcspn(amagic, " ");
- bmagic += strcspn(bmagic, " ");
+ if (has_crcs) {
+ amagic += strcspn(amagic, " ");
+ bmagic += strcspn(bmagic, " ");
+ }
return strcmp(amagic, bmagic) == 0;
}
#else
@@ -981,7 +984,8 @@
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 @@
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;