mpatch: avoid integer overflow in combine() (SEC) All the callers of this function can handle a NULL return, so that appears to be the "safe" way to report an error.

mpatch: avoid integer overflow in mpatch_decode (SEC)

mpatch: fix UB integer overflows in discard() (SEC)

mpatch: fix UB in int overflows in gather() (SEC)

mpatch: introduce a safesub() helper as well Same reason as safeadd().

mpatch: introduce a safeadd() helper to work around UB int overflow We're about to make extensive use of this. This change duplicates some stdbool.h portability hacks from cext/util.h. We should probably clean that up in the future, but we'll skip that for now in order to make security backports easier.

mpatch: ensure fragment start isn't past the end of orig (SEC) Caught by oss-fuzz fuzzer during development. This defect is OVE-20180430-0004. A CVE has not been obtained as of this writing.

mpatch: protect against underflow in mpatch_apply (SEC) Also caught by oss-fuzz fuzzer during development. This defect is OVE-20180430-0002. A CVE has not been obtained as of this writing.

mpatch: be more careful about parsing binary patch data (SEC) It appears to have been possible to trivially walk off the end of an allocated region with a malformed patch. Oops. Caught when writing an mpatch fuzzer for oss-fuzz. This defect is OVE-20180430-0001. A CVE has not been obtained as of this writing.

zstandard: pull in bug fixes from upstream 0.9.1 release (issue5884) This changeset contains the meaningful code changes from python-zstandard's 0.9.1 release. The main fix is to restore support for compiling with mingw.