[PATCH BlueZ v1 0/8] Replace the name2utf8 copies with str2utf8

From: Luiz Augusto von Dentz <[email protected]>

There are five near copies of the same helper turning a remote name into
a UTF-8 string, in monitor/att.c, profiles/audio/mcp.c,
profiles/gap/gas.c, src/eir.c and src/shared/ad.c, and none of them
agree with each other.

The copy in src/eir.c does not clamp the length before copying into a
fixed size stack buffer, and eir_parse() can hand it 253 bytes for a 250
byte buffer, so a remote device can overflow it with a long name in an
advertising report. That is fixed first and on its own so it can be
backported.

The rest replaces the copies with a single str2utf8() in src/shared/util
and drops around 120 lines.

Three things change behaviour and are worth a look:

- Most of the copies truncated the name at the first ill-formed
  sequence, throwing the rest away, and the monitor replaced every
  non-ASCII byte with a space, mangling the valid part of the name.
  str2utf8() replaces only the ill-formed sequences with U+FFFD, so a
  name is no longer cut short by one bad byte in the middle. The
  unit/test-eir expectations are updated to match.

- strnlenutf8(), and with it strisutf8() and strtoutf8(), only checked
  the shape of the bytes, so it accepted overlong encodings, UTF-16
  surrogates and code points past U+10FFFF. Those reach D-Bus, which
  does validate UTF-8 and rejects them. It now validates as per table
  3-7 of the Unicode Standard.

- btd_device_set_name() cut the name at 248 bytes with strncpy(),
  without regard for where the characters start and end, so a longer
  name could be left with a partial sequence and be rejected by D-Bus.
  It now truncates on a character boundary. It also loses the doubled
  "device" in its name.

str2utf8() and strtoutf8() were checked against Python's UTF-8 decoder
over every one and two byte sequence, a sample of the three byte ones
and 200000 random inputs, with no mismatch.

Luiz Augusto von Dentz (8):
  eir: Fix stack buffer overflow when parsing the remote name
  shared/util: Make strnlenutf8 reject ill-formed sequences
  shared/util: Add str2utf8
  unit/test-util: Add str2utf8 tests
  Replace the name2utf8 copies with str2utf8
  device: Fix the name truncation splitting UTF-8 sequences
  device: Rename btd_device_device_set_name to btd_device_set_name
  unit/test-util: Cover strtoutf8 with the str2utf8 tests

 monitor/att.c        |  66 +++++++--------------
 plugins/neard.c      |   2 +-
 plugins/sixaxis.c    |   2 +-
 profiles/audio/mcp.c |  24 +-------
 profiles/gap/gas.c   |  22 +------
 src/adapter.c        |   4 +-
 src/device.c         |  14 ++++-
 src/device.h         |   2 +-
 src/eir.c            |  20 +------
 src/shared/ad.c      |  20 +++----
 src/shared/util.c    | 136 ++++++++++++++++++++++++++++++++++---------
 src/shared/util.h    |   7 +++
 unit/test-eir.c      |   7 ++-
 unit/test-util.c     | 121 ++++++++++++++++++++++++++++++++++++++
 14 files changed, 294 insertions(+), 153 deletions(-)

-- 
2.54.0