[klibc] cpio: Fix possible crash on 64-bit systems

[klibc] cpio: Fix possible crash on 64-bit systems

Origin: https://git.kernel.org/pub/scm/libs/klibc/klibc.git/commit/?id=2e48a12ab1e30d43498c2d53e878a11a1b5102d5
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2021-31871

copyin_link() tries to allocate (unsigned int)c_filesize + 1 bytes.
If c_filesize == UINT_MAX, this works out as 0 bytes, resulting in a
null pointer and a subsequent SIGSEGV.

The previous commit made this impossible on 32-bit systems.

CVE-2021-31871

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Name 0040-klibc-cpio-Fix-possible-crash-on-64-bit-systems.patch