SECURITY UPDATE: Fix out of bounds read in .ar and .tar implementation (CVE-2020-3810)
When normalizing ar member names by removing trailing whitespace
and slashes, an out-out-bound read can be caused if the ar member
name consists only of such characters, because the code did not
stop at 0, but would wrap around and continue reading from the
stack, without any limit.
Add a check to abort if we reached the first character in the
name, effectively rejecting the use of names consisting just
of slashes and spaces.
Furthermore, certain error cases in arfile.cc and extracttar.cc have
included member names in the output that were not checked at all and
might hence not be nul terminated, leading to further out of bound reads.
SECURITY UPDATE: content injection in http method (CVE-2019-3462)
This fixes a security issue that can be exploited to inject arbritrary debs
or other files into a signed repository as followed:
(1) Server sends a redirect to somewhere%0a<headers for the apt method> (where %0a is
\n encoded)
(2) apt method decodes the redirect (because the method encodes the URLs before
sending them out), writting something like
somewhere\n
<headers>
into its output
(3) apt then uses the headers injected for validation purposes.
