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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>
This commit is contained in:
Rusty Russell 2008-05-09 16:25:28 +10:00 committed by Linus Torvalds
parent a5dd697074
commit 91e37a793b
2 changed files with 13 additions and 9 deletions
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6
init/Kconfig
View File

@ -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"

16
kernel/module.c
View File

@ -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;