Release libgit2 v0.27.6 · libgit2/libgit2 (original) (raw)

This as a security release fixing the following list of issues:

• The function family git__strtol is used to parse integers
  from a buffer. As the functions do not take a buffer length as
  argument, they will scan either until the end of the current
  number or until a NUL byte is encountered. Many callers have
  been misusing the function and called it on potentially
  non-NUL-terminated buffers, resulting in possible out-of-bounds
  reads. Callers have been fixed to use git__strntol functions
  instead and git__strtol functions were removed.
• The function git__strntol64 relied on the undefined behavior
  of signed integer overflows. While the code tried to detect
  such overflows after they have happened, this is unspecified
  behavior and may lead to weird behavior on uncommon platforms.
• In the case where git__strntol32 was unable to parse an
  integer because it doesn't fit into an int32_t, it printed an
  error message containing the string that is currently being
  parsed. The code didn't truncate the string though, which
  caused it to print the complete string until a NUL byte is
  encountered and not only the currently parsed number. In case
  where the string was not NUL terminated, this could have lead
  to an out-of-bounds read.
• When parsing tags, all unknown fields that appear before the
  tag message are skipped. This skipping is done by using a plain
  strstr(buffer, "\n\n") to search for the two newlines that
  separate tag fields from tag message. As it is not possible to
  supply a buffer length to strstr, this call may skip over the
  buffer's end and thus result in an out of bounds read. As
  strstr may return a pointer that is out of bounds, the
  following computation of buffer_end - buffer will overflow
  and result in an allocation of an invalid length. Note that
  when reading objects from the object database, we make sure to
  always NUL terminate them, making the use of strstr safe.
• When parsing the "encoding" field of a commit, we may perform
  an out of bounds read due to using git__prefixcmp instead of
  git__prefixncmp. This can result in the parsed commit object
  containing uninitialized data in both its message encoding and
  message fields. Note that when reading objects from the object
  database, we make sure to always NUL terminate them, making the
  use of strstr safe.