module: harden ELF info handling
5fdc7db6 ("module: setup load info before module_sig_check()") moved the ELF setup, so that it was done before the signature check. This made the module name available to signature error messages. However, the checks for ELF correctness in setup_load_info are not sufficient to prevent bad memory references due to corrupted offset fields, indices, etc. So, there's a regression in behavior here: a corrupt and unsigned (or badly signed) module, which might previously have been rejected immediately, can now cause an oops/crash. Harden ELF handling for module loading by doing the following: - Move the signature check back up so that it comes before ELF initialization. It's best to do the signature check to see if we can trust the module, before using the ELF structures inside it. This also makes checks against info->len more accurate again, as this field will be reduced by the length of the signature in mod_check_sig(). The module name is now once again not a...
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ebfac7b7