The exact byte count of the delta base file is important.
The test-delta helper will feed it to patch_delta(), which
will barf if it doesn't match the size byte given in the
delta. Using "echo" may end up with unexpected line endings
on some platforms (e.g,. "\r\n" instead of just "\n").
This actually wouldn't cause the test to fail (since we
already expect test-delta to complain about these bogus
deltas), but would mean that we're not exercising the code
we think we are.
Let's use printf instead (which we already trust to give us
byte-perfect output when we generate the deltas).
While we're here, let's tighten the 5-byte result size used
in the "truncated copy parameters" test. This just needs to
have enough room to attempt to parse the bogus copy command,
meaning 2 is sufficient. Using 5 was arbitrary and just
copied from the base size; since those no longer match, it's
simply confusing. Let's use a more meaningful number.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we see a delta command instructing us to copy bytes
from the base, we have to read the offset and size from the
delta stream. We do this without checking whether we're at
the end of the stream, meaning we may read past the end of
the buffer.
In practice this isn't exploitable in any interesting way
because:
1. Deltas are always in packfiles, so we have at least a
20-byte trailer that we'll end up reading.
2. The worst case is that we try to perform a nonsense
copy from the base object into the result, based on
whatever was in the pack stream next. In most cases
this will simply fail due to our bounds-checks against
the base or the result.
But even if you carefully constructed a pack stream for
which it succeeds, it wouldn't perform any delta
operation that you couldn't have simply included in a
non-broken form.
But obviously it's poor form to read past the end of the
buffer we've been given. Unfortunately there's no easy way
to do a single length check, since the number of bytes we
need depends on the number of bits set in the initial
command byte. So we'll just check each byte as we parse. We
can hide the complexity in a macro; it's ugly, but not as
ugly as writing out each individual conditional.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When applying a delta, if we see an opcode that cannot be
fulfilled (e.g., asking to write more bytes than the
destination has left), we break out of our parsing loop but
don't signal an explicit error. We rely on the sanity check
after the loop to see if we have leftover delta bytes or
didn't fill our result buffer.
This can silently ignore corruption when the delta buffer
ends with a bogus command and the destination buffer is
already full. Instead, let's jump into the error handler
directly when we see this case.
Note that the tests also cover the "bad opcode" case, which
already handles this correctly.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
If `cmd` is in the range [0x01,0x7f] and `cmd > top-data`, the
`memcpy(out, data, cmd)` can copy out-of-bounds data from after `delta_buf`
into `dst_buf`.
This is not an exploitable bug because triggering the bug increments the
`data` pointer beyond `top`, causing the `data != top` sanity check after
the loop to trigger and discard the destination buffer - which means that
the result of the out-of-bounds read is never used for anything.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We don't have any tests that specifically check boundary
cases in patch_delta(). It obviously gets exercised by tests
which read from packfiles, but it's hard to create packfiles
with bogus deltas.
So let's cover some obvious boundary cases:
1. commands that overflow the result buffer
a. literal content from the delta
b. copies from a base
2. commands where the source isn't large enough
a. literal content from a truncated delta
b. copies that need more bytes than the base has
3. copy commands who parameters are truncated
And indeed, we have problems with both 2a and 3. I've marked
these both as expect_failure, though note that because they
involve reading past the end of a buffer, they will
typically only be caught when run under valgrind or ASan.
There's one more test here, too, which just applies a basic
delta. Since all of the other tests expect failure and we
don't otherwise use "test-tool delta" in the test suite,
this gives a sanity check that the tool works at all.
These are based on an earlier patch by Jann Horn
<jannh@google.com>.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.
The backquoted form is the traditional method for command
substitution, and is supported by POSIX. However, all but the
simplest uses become complicated quickly. In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.
The patch was generated by:
for _f in $(find . -name "*.sh")
do
perl -i -pe 'BEGIN{undef $/;} s/`(.+?)`/\$(\1)/smg' "${_f}"
done
and then carefully proof-read.
Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As of the last commit, we can use "perl" instead of
"$PERL_PATH" when running tests, as the former is now a
function which uses the latter. As the shorter "perl" is
easier on the eyes, let's switch to using it everywhere.
This is not quite a mechanical s/$PERL_PATH/perl/
replacement, though. There are some places where we invoke
perl from a script we generate on the fly, and those scripts
do not have access to our internal shell functions. The
result can be double-checked by running:
ln -s /bin/false bin-wrappers/perl
make test
which continues to pass even after this patch.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we try to load an object from disk and fail, our
general strategy is to see if we can get it from somewhere
else (e.g., a loose object). That lets users fix corruption
problems by copying known-good versions of objects into the
object database.
We already handle the case where we were not able to read
the delta from disk. However, when we find that the delta we
read does not apply, we simply die. This case is harder to
trigger, as corruption in the delta data itself would
trigger a crc error from zlib. However, a corruption that
pointed us at the wrong delta base might cause it.
We can do the same "fail and try to find the object
elsewhere" trick instead of dying. This not only gives us a
chance to recover, but also puts us on code paths that will
alert the user to the problem (with the current message,
they do not even know which sha1 caused the problem).
Note that unlike some other pack corruptions, we do not
recover automatically from this case when doing a repack.
There is nothing apparently wrong with the delta, as it
points to a valid, accessible object, and we realize the
error only when the resulting size does not match up. And in
theory, one could even have a case where the corrupted size
is the same, and the problem would only be noticed by
recomputing the sha1.
We can get around this by recomputing the deltas with
--no-reuse-delta, which our test does (and this is probably
good advice for anyone recovering from pack corruption).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This test corrupts pack objects by using "dd" with a seek
command. It passes "count=1 bs=1" to munge just a single
byte. However, the test added in commit b3118bdc wants to
munge two bytes, and the second byte of corruption is
silently ignored.
This turned out not to impact the test, however. The idea
was to reduce the "size of this entry" part of the header so
that zlib runs out of input bytes while inflating the entry.
That header is two bytes long, and the test reduced the
value of both bytes; since we experience the problem if we
are off by even 1 byte, it is sufficient to munge only the
first one.
Even though the test would have worked with only a single
byte munged, and we could simply tweak the test to use a
single byte, it makes sense to lift this 1-byte restriction
from do_corrupt_object. It will allow future tests that do
need to change multiple bytes to do so.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Otherwise it will be split at a space after "Program" when it is set
to "\\Program Files\perl" or something silly like that.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
GIT-BUILD-OPTIONS defines PERL_PATH to be used in the test suite. Only a
few tests already actually use this variable when perl is needed. The
other test just call 'perl' and it might happen that the wrong perl
interpreter is used.
This becomes problematic on Windows, when the perl interpreter that is
compiled and installed on the Windows system is used, because this perl
interpreter might introduce some unexpected LF->CRLF conversions.
This patch makes sure that $PERL_PATH is used everywhere in the test suite
and that the correct perl interpreter is used.
Signed-off-by: Vincent van Ravesteijn <vfr@lyx.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some types of corruption to a pack may confuse the deflate stream
which stores an object. In Andy's reported case a 36 byte region
of the pack was overwritten, leading to what appeared to be a valid
deflate stream that was trying to produce a result larger than our
allocated output buffer could accept.
Z_BUF_ERROR is returned from inflate() if either the input buffer
needs more input bytes, or the output buffer has run out of space.
Previously we only considered the former case, as it meant we needed
to move the stream's input buffer to the next window in the pack.
We now abort the loop if inflate() returns Z_BUF_ERROR without
consuming the entire input buffer it was given, or has filled
the entire output buffer but has not yet returned Z_STREAM_END.
Either state is a clear indicator that this loop is not working
as expected, and should not continue.
This problem cannot occur with loose objects as we open the entire
loose object as a single buffer and treat Z_BUF_ERROR as an error.
Reported-by: Andy Isaacson <adi@hexapodia.org>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We do not have /dev/zero on Windows. This replaces it by data generated
with printf, perl, or echo. Most of the cases do not depend on that the
data is a stream of zero bytes, so we use something printable; nor is an
unlimited stream of data needed, so we produce only as many bytes as the
test cases need.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
printf "\x01" is bad; write printf "\001" for portability.
Testing with dash is a good way to find this kind of POSIX.1 violation
breakages.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The perldiag(1) has following to say about this:
"Can't do inplace edit without backup"
(F) You're on a system such as MS-DOS that gets confused if
you try reading from a deleted (but still opened) file. You
have to say -i.bak, or some such.
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
