kld: Reject kernel modules with PT_LOAD segments where filesz > memsz

[jhb]

Summary

All sorts of places in the ELF loading code assume that filesz <=
memsz, so check that explicitly up front.

Reported by: Jane Smith <[e-mail]> (via D57785)

[jrtc27]

I just used their email address for Reported by because given (a) the lack of history with the project (b) no trace of them existing anywhere else online (c) the low-quality suspicious nature of the patches (d) the name being one of *the* quintessential placeholders, I am suspicious as to whether it's their real name.

[jhb]

In D58542#1343670, @jrtc27 wrote:

I just used their email address for Reported by because given (a) the lack of history with the project (b) no trace of them existing anywhere else online (c) the low-quality suspicious nature of the patches (d) the name being one of *the* quintessential placeholders, I am suspicious as to whether it's their real name.

It might indeed be a placeholder (though who knows for anyone's name unless you've met them in person really), but it's already present in the author field of various other commits in src (including one misspelling as Jana):

> git log --author thebugfixers --format="%h %an <%ae>"
9724f3f89749 Jane Smith <[e-mail]>
be23edc1e402 Jana Smith <[e-mail]>
635ad6f2ec97 Jane Smith <[e-mail]>