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[77.189.33.153]) by smtp.gmail.com with ESMTPSA id l20sm29156738wrb.93.2018.12.09.20.28.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 09 Dec 2018 20:28:45 -0800 (PST) Date: Mon, 10 Dec 2018 05:28:43 +0100 From: SZEDER =?utf-8?B?R8OhYm9y?= To: Junio C Hamano Cc: Josh Steadmon , git@vger.kernel.org, stolee@gmail.com, avarab@gmail.com, peff@peff.net Subject: Re: [PATCH v3 2/3] commit-graph: fix buffer read-overflow Message-ID: <20181210042843.GQ30222@szeder.dev> References: <675d58ecea2f315bd05d2a21f6a473e9de1105a0.1544221121.git.steadmon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sun, Dec 09, 2018 at 01:01:29PM +0900, Junio C Hamano wrote: > Josh Steadmon writes: > > > diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh > > index 5fe21db99f..5b6b44b78e 100755 > > --- a/t/t5318-commit-graph.sh > > +++ b/t/t5318-commit-graph.sh > > @@ -366,24 +366,30 @@ GRAPH_OCTOPUS_DATA_OFFSET=$(($GRAPH_COMMIT_DATA_OFFSET + \ > > GRAPH_BYTE_OCTOPUS=$(($GRAPH_OCTOPUS_DATA_OFFSET + 4)) > > GRAPH_BYTE_FOOTER=$(($GRAPH_OCTOPUS_DATA_OFFSET + 4 * $NUM_OCTOPUS_EDGES)) > > > > -# usage: corrupt_graph_and_verify > > +# usage: corrupt_graph_and_verify [] > > # Manipulates the commit-graph file at the position > > -# by inserting the data, then runs 'git commit-graph verify' > > +# by inserting the data, optionally zeroing the file > > +# starting at , then runs 'git commit-graph verify' > > # and places the output in the file 'err'. Test 'err' for > > # the given string. > > corrupt_graph_and_verify() { > > pos=$1 > > data="${2:-\0}" > > grepstr=$3 > > + orig_size=$(stat --format=%s $objdir/info/commit-graph) > > "stat(1)" is not so portable, so you'll get complaints from minority > platform users later. So is "truncate(1)". I complain: this patch breaks on macOS (on Travis CI), but in a curious way. First, 'stat' in the above line errors out with: +++stat --format=%s .git/objects/info/commit-graph stat: illegal option -- - usage: stat [-FlLnqrsx] [-f format] [-t timefmt] [file ...] Alas, this doesn't immediately fail the test, because it's not part of the &&-chain. > > + zero_pos=${4:-${orig_size}} No && here, either. > > cd "$TRASH_DIRECTORY/full" && > > test_when_finished mv commit-graph-backup $objdir/info/commit-graph && > > cp $objdir/info/commit-graph commit-graph-backup && > > printf "$data" | dd of="$objdir/info/commit-graph" bs=1 seek="$pos" conv=notrunc && > > + truncate --size=$zero_pos $objdir/info/commit-graph && ++truncate --size= .git/objects/info/commit-graph t5318-commit-graph.sh: line 385: truncate: command not found Note that even if 'truncate' were available, it would most likely complain about the empty '--size=' argument resulting from the 'stat' error above. Alas, this doesn't fail the test, either, because ... > > + truncate --size=$orig_size $objdir/info/commit-graph && > > test_must_fail git commit-graph verify 2>test_err && > > grep -v "^+" test_err >err ... here the &&-chain was broken already before this patch. However, since this above command was not executed due to the missing 'truncate', it didn't have a chance to create the 'err' file, ... > > test_i18ngrep "$grepstr" err ... so 'test_i18ngrep' can't find the file, which triggers its linting error, finally aborting the whole test script. > > } > > > > + Stray newline. > > test_expect_success 'detect bad signature' ' > > corrupt_graph_and_verify 0 "\0" \ > > "graph signature" > > @@ -484,6 +490,11 @@ test_expect_success 'detect invalid checksum hash' ' > > "incorrect checksum" > > ' > > > > +test_expect_success 'detect incorrect chunk count' ' > > + corrupt_graph_and_verify $GRAPH_BYTE_CHUNK_COUNT "\xff" \ > > Implementations of printf(1) may not grok "\xff" as a valid > representation of "\377". The shell built-in of dash(1) for example > would not work with this. > > > + "chunk lookup table entry missing" $GRAPH_CHUNK_LOOKUP_OFFSET > > +' > > + > > test_expect_success 'git fsck (checks commit-graph)' ' > > cd "$TRASH_DIRECTORY/full" && > > git fsck &&