libkmod: Avoid OOB with huge ELF files

libkmod: Avoid OOB with huge ELF files

On 32 bit systems it is possible to trigger an out of boundary write
with excessively huge ELF files.

The calculation of required memory for char pointer vector and strings
might overflow, leading to an allocation which is too small. Subsequent
memcpy leads to an out of boundary write.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/149
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>