Commit Graph

3 Commits

Author SHA1 Message Date
Bill Richardson
c4e92af85a Address some security concerns in the cgpt tool.
1. Check for potential integer overflow in sector_bytes * sector_count.
2. Added O_NOFOLLOW to open() call - Is this enough?
3. Passing buffer length to GuidToStr(), PMBRToStr().
4. Use unsigned int in GetEntry() to determine stride.
5. Address conversion between UTF16 and UTF8.

Note: The UTF conversion is complex and troublesome, and needs careful
consideration to get right. For now, I've just forced the interpretation of
the partition name to 7-bit ASCII. That's sufficient for the needs of Chrome
OS, and I can file a new issue to handle UTF correctly.

BUG=chrome-os-partner:705
TEST=manual

Running "make runtests" invokes the tests/run_cgpt_tests.sh script, which checks the behavior and output of the cgpt tool.

Review URL: http://codereview.chromium.org/3594010

Change-Id: I5fd29796d8c929527e0cfbc6d5ccbcdc77502c6b
2010-10-12 07:33:15 -07:00
Bill Richardson
962483c1e2 This fixes the EFI BIOS boot problems introduced with cgpt.
There were two changes. First, we need to pack the GPT header to make it
match the spec (duh). Second, there's a subtle bug in how the BIOS recovers
from corrupted headers. The EFI spec says that the primary GPT header must
be at sector 1 (counting from zero) and the secondary GPT header must be at
the last sector on the drive. The BIOS correctly looks in those locations to
find the headers. However, if the secondary GPT header is invalid (as it
usually is due to our build process), the BIOS is supposed to update it from
the primary header. In this case, rather than write to the last sector on
the drive where it just looked, the BIOS trusts the alternate_lba field of
the primary header. That field is supposed to point to the secondary header
location, but the BIOS just blindly uses it no matter where it points. The
cgpt tool wasn't initializing that field, so it pointed to sector 0, which
is the PMBR. The BIOS overwrote that, resulting in an unbootable drive.

Review URL: http://codereview.chromium.org/2844006
2010-06-15 21:07:18 -07:00
Bill Richardson
f1372d9109 Nearly complete rewrite of cgpt tool.
This fixes a number of bugs, adds a bunch of commands, and essentially makes
cgpt ready to use as a replacement for gpt. Still to do is to add commands
and options that will let it generated intentionally bad partitions, for use
in testing.

Review URL: http://codereview.chromium.org/2719008
2010-06-11 09:15:55 -07:00