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authorRusty Russell <rusty@rustcorp.com.au>2008-05-09 16:25:28 +1000
committerLinus Torvalds <torvalds@linux-foundation.org>2008-05-09 07:45:18 -0700
commit91e37a793b5a9436a2d12b2f0a8f52db3a133e1d (patch)
tree6ddf17ad786fa2a42ef79aa4f7873c79c1e17a89 /kernel
parenta5dd69707424a35d2d2cc094e870f595ad61e916 (diff)
downloadlinux-91e37a793b5a9436a2d12b2f0a8f52db3a133e1d.tar.gz
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/module.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/module.c b/kernel/module.c
index 2584c0e2762d..f5e9491ef7ac 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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)
 {
-	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 @@ 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;