[Security] Bump protobuf from 1.4.2 to 1.7.5

[dependabot-preview]

Bumps protobuf from 1.4.2 to 1.7.5. This update includes security fixes.

Vulnerabilities fixed

Sourced from The RustSec Advisory Database.

Out of Memory in stream::read_raw_bytes_into()
Affected versions of this crate called Vec::reserve() on user-supplied input.

This allows an attacker to cause an Out of Memory condition while calling the
vulnerable method on untrusted data.

Patched versions: ^1.7.5; >= 2.6.0
Unaffected versions: none

Changelog

Sourced from protobuf's changelog.

Changelog

[Unreleased]

Backward compatibility

Version 3.0 is backward incompatible with 2.0 version. Changes are listed here:

• Enum fields are now
  generated as ProtobufEnumOrUnknown<E>
• Nested messages are now
  generated in nested mods
• All fields are public now except optional or repeated fields when syntax = "proto2",
  but message fields are public even when syntax = "proto2"
• Field accessors (getters and setters) are not generated by default for public fields
• Remove global parse_length_delimited*
  functions
• PartialEq with large number of fields
  now panics.
  Previosly it could cause stack overflow in the Rust compiler.
• Change message_down_cast* functions
  signatures
• Remove descriptorx from protobuf
  crate

New features

• Option to store repeated message fields in Vec instead of RepeatedField. This option may be turned on by default later.
• Similarly, option to store singular field on Option instead of SingularPtrField, which also may be turned on by default later.
• generate_getter option to disable generation of getters functions.
• Flush CodedOutputStream on drop

Improvements

• JSON printing/parsing implemented
• Text format parsing is implemented (previously it was only possible to print to text format)
• Reflection can now mutate data (previously reflection could only read data)
• Unsafe code is not used in generated code
  (although protobuf implementation does a couple of unsafe calls).

[2.6 Unreleased]

• Fix Hash of
  UnknownFields

[2.6.0] - 2019-05-19

• lite_runtime rust-protobuf option
• Fix OOM on malformed input

... (truncated)

Commits

• 941fbf4 Bump version
• a3438d5 Fix test compilation for Rust 1.23
• c99e6a4 update-version is external crate now
• 95d9da2 Fix compilation with Rust 1.23
• a839f7b Fuzz testing with Read trait and fix OOM on incorrect input
• 41b5e57 Fix test on travis (again)
• bd3b90a Fix tests when protoc < 3
• ea5779b Rename cfg(proto3) to cfg(protoc3) in tests
• be77766 Bump version
• 2ee5003 Properly decode maps with unset keys or values
• Additional commits viewable in compare view

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