OCaml before 4.03.0 does not properly handle sign extensions, which allows remote attackers to conduct buffer overflow attacks or obtain sensitive information as demonstrated by a long string to the String.copy function.

OCaml before 4.03.0 does not properly handle sign extensions, which allows remote attackers to conduct buffer overflow attacks or obtain sensitive information as demonstrated by a long string to the String.copy function.

ocaml-4.03.0-1.3 on GA media

Affected: opam: ocaml

## Bug description

OCaml versions 4.02.3 and earlier have a runtime bug that, on 64-bit platforms, causes sizes arguments to an internal memmove call to be sign-extended from 32 to 64-bits before being passed to the memmove function.

This leads arguments between 2GiB and 4GiB to be interpreted as larger than they are (specifically, a bit below 2^64), causing a buffer overflow.

Arguments between 4GiB and 6GiB are interpreted as 4GiB smaller than they should be, causing a possible information leak.

This commit fixes the bug: https://github.com/ocaml/ocaml/commit/659615c7b100a89eafe6253e7a5b9d84d0e8df74#diff-a97df53e3ebc59bb457191b496c90762 The function caml_bit_string is called indirectly from such functions as String.copy. String.copy for instance is supposed to be a "safe" function for which OCaml's memory safety guarantees apply.

ocaml: sizes arguments are sign-extended from 32 to 64 bits

Security update for ocaml

Affected: Ubuntu:14.04:LTS: ocaml, Ubuntu:Pro:16.04:LTS: ocaml

OCaml before 4.03.0 does not properly handle sign extensions, which allows remote attackers to conduct buffer overflow attacks or obtain sensitive information as demonstrated by a long string to the String.copy function.