9de345cb27
The wincred credential helper uses a static buffer ("target") as a
unique key for storing and comparing against internal storage. It does
this by building up a string is supposed to look like:
git:$PROTOCOL://$USERNAME@$HOST/@PATH
However, the static "target" buffer is declared as a wide string with no
more than 1,024 wide characters. The first call to wcsncat() is almost
correct (it copies no more than ARRAY_SIZE(target) wchar_t's), but does
not account for the trailing NUL, introducing an off-by-one error.
But subsequent calls to wcsncat() have an additional problem on top of
the off-by-one. They do not account for the length of the existing
wide string being built up in 'target'. So the following:
$ perl -e '
my $x = "x" x 1_000;
print "protocol=$x\nhost=$x\nusername=$x\npath=$x\n"
' |
C\:/Program\ Files/Git/mingw64/libexec/git-core/git-credential-wincred.exe get
will result in a segmentation fault from over-filling buffer.
This bug is as old as the wincred helper itself, dating back to
a6253da0f3 (contrib: add win32 credential-helper, 2012-07-27). Commit
8b2d219a3d (wincred: improve compatibility with windows versions,
2013-01-10) replaced the use of strncat() with wcsncat(), but retained
the buggy behavior.
Fix this by using a "target_append()" helper which accounts for both the
length of the existing string within the buffer, as well as the trailing
NUL character.
Reported-by: David Leadbeater <dgl@dgl.cx>
Helped-by: David Leadbeater <dgl@dgl.cx>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Git - fast, scalable, distributed revision control system
Git is a fast, scalable, distributed revision control system with an unusually rich command set that provides both high-level operations and full access to internals.
Git is an Open Source project covered by the GNU General Public License version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
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If git has been correctly installed, then the tutorial can also be
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- stupid. contemptible and despicable. simple. Take your pick from the dictionary of slang.
- "global information tracker": you're in a good mood, and it actually works for you. Angels sing, and a light suddenly fills the room.
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