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>
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2 changed files with 13 additions and 9 deletions
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@ -845,9 +845,9 @@ config MODULE_FORCE_LOAD
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depends on MODULES
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default n
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help
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This option allows loading of modules even if that would set the
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'F' (forced) taint, due to lack of version info. Which is
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usually a really bad idea.
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Allow loading of modules without version information (ie. modprobe
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--force). Forced module loading sets the 'F' (forced) taint flag and
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is usually a really bad idea.
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config MODULE_UNLOAD
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bool "Module unloading"
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@ -957,11 +957,14 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
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return check_version(sechdrs, versindex, "struct_module", mod, crc);
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}
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/* First part is kernel version, which we ignore. */
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static inline int same_magic(const char *amagic, const char *bmagic)
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/* First part is kernel version, which we ignore if module has crcs. */
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static inline int same_magic(const char *amagic, const char *bmagic,
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bool has_crcs)
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{
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amagic += strcspn(amagic, " ");
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bmagic += strcspn(bmagic, " ");
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if (has_crcs) {
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amagic += strcspn(amagic, " ");
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bmagic += strcspn(bmagic, " ");
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}
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return strcmp(amagic, bmagic) == 0;
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}
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#else
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@ -981,7 +984,8 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
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return 1;
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}
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static inline int same_magic(const char *amagic, const char *bmagic)
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static inline int same_magic(const char *amagic, const char *bmagic,
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bool has_crcs)
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{
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return strcmp(amagic, bmagic) == 0;
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}
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@ -1874,7 +1878,7 @@ static struct module *load_module(void __user *umod,
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err = try_to_force_load(mod, "magic");
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if (err)
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goto free_hdr;
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} else if (!same_magic(modmagic, vermagic)) {
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} else if (!same_magic(modmagic, vermagic, versindex)) {
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printk(KERN_ERR "%s: version magic '%s' should be '%s'\n",
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mod->name, modmagic, vermagic);
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err = -ENOEXEC;
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