From: Josh Steadmon <steadmon@google.com>
To: git@vger.kernel.org
Cc: gitster@pobox.com, stolee@gmail.com, avarab@gmail.com,
peff@peff.net, szeder.dev@gmail.com
Subject: [PATCH v4 2/3] commit-graph: fix buffer read-overflow
Date: Thu, 13 Dec 2018 11:43:57 -0800 [thread overview]
Message-ID: <80b5662f30cb87210385a6bd26e037ce39e46b6d.1544729841.git.steadmon@google.com> (raw)
In-Reply-To: <cover.1544729841.git.steadmon@google.com>
fuzz-commit-graph identified a case where Git will read past the end of
a buffer containing a commit graph if the graph's header has an
incorrect chunk count. A simple bounds check in parse_commit_graph()
prevents this.
Signed-off-by: Josh Steadmon <steadmon@google.com>
---
commit-graph.c | 14 ++++++++++++--
t/t5318-commit-graph.sh | 16 +++++++++++++---
2 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/commit-graph.c b/commit-graph.c
index 07dd410f3c..836d65a1d3 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -165,10 +165,20 @@ struct commit_graph *parse_commit_graph(void *graph_map, int fd,
last_chunk_offset = 8;
chunk_lookup = data + 8;
for (i = 0; i < graph->num_chunks; i++) {
- uint32_t chunk_id = get_be32(chunk_lookup + 0);
- uint64_t chunk_offset = get_be64(chunk_lookup + 4);
+ uint32_t chunk_id;
+ uint64_t chunk_offset;
int chunk_repeated = 0;
+ if (data + graph_size - chunk_lookup <
+ GRAPH_CHUNKLOOKUP_WIDTH) {
+ error(_("chunk lookup table entry missing; graph file may be incomplete"));
+ free(graph);
+ return NULL;
+ }
+
+ chunk_id = get_be32(chunk_lookup + 0);
+ chunk_offset = get_be64(chunk_lookup + 4);
+
chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
index 5fe21db99f..a1b5a75882 100755
--- a/t/t5318-commit-graph.sh
+++ b/t/t5318-commit-graph.sh
@@ -366,21 +366,26 @@ 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 <position> <data> <string>
+# usage: corrupt_graph_and_verify <position> <data> <string> [<zero_pos>]
# 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 <zero_pos>, 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=$3
+ orig_size=$(wc -c < $objdir/info/commit-graph) &&
+ zero_pos=${4:-${orig_size}} &&
cd "$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 &&
+ dd of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" count=0 &&
+ dd if=/dev/zero of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" count=$(($orig_size - $zero_pos)) &&
test_must_fail git commit-graph verify 2>test_err &&
- grep -v "^+" test_err >err
+ grep -v "^+" test_err >err &&
test_i18ngrep "$grepstr" err
}
@@ -484,6 +489,11 @@ test_expect_success 'detect invalid checksum hash' '
"incorrect checksum"
'
+test_expect_success 'detect incorrect chunk count' '
+ corrupt_graph_and_verify $GRAPH_BYTE_CHUNK_COUNT "\377" \
+ "chunk lookup table entry missing" $GRAPH_CHUNK_LOOKUP_OFFSET
+'
+
test_expect_success 'git fsck (checks commit-graph)' '
cd "$TRASH_DIRECTORY/full" &&
git fsck &&
--
2.20.0.rc2.10.g21101b961a
next prev parent reply other threads:[~2018-12-13 19:44 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 22:32 [PATCH 0/2] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-05 22:32 ` [PATCH 1/2] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-05 22:48 ` Ævar Arnfjörð Bjarmason
2018-12-06 1:00 ` Josh Steadmon
2018-12-06 1:32 ` Junio C Hamano
2018-12-06 1:41 ` Junio C Hamano
2018-12-06 4:47 ` Junio C Hamano
2018-12-05 22:32 ` [PATCH 2/2] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-06 13:11 ` Derrick Stolee
2018-12-06 20:20 ` [PATCH v2 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-06 20:20 ` [PATCH v2 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-06 20:20 ` [PATCH v2 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-07 9:07 ` Jeff King
2018-12-07 13:33 ` Derrick Stolee
2018-12-06 20:20 ` [PATCH v2 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-07 22:27 ` [PATCH v3 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2018-12-09 4:01 ` Junio C Hamano
2018-12-10 4:28 ` SZEDER Gábor
2018-12-10 21:58 ` Josh Steadmon
2018-12-10 21:56 ` Josh Steadmon
2018-12-11 9:50 ` Jeff King
2018-12-07 22:27 ` [PATCH v3 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2018-12-13 19:43 ` Josh Steadmon [this message]
2019-01-12 10:57 ` [PATCH v4 2/3] commit-graph: fix buffer read-overflow SZEDER Gábor
2019-01-15 19:58 ` Josh Steadmon
2018-12-13 19:43 ` [PATCH v4 3/3] Makefile: correct example fuzz build Josh Steadmon
2018-12-18 17:35 ` [PATCH v4 0/3] Add commit-graph fuzzer and fix buffer overflow Jeff King
2018-12-18 21:05 ` Josh Steadmon
2018-12-19 15:51 ` Jeff King
2018-12-20 19:35 ` Johannes Schindelin
2018-12-20 20:11 ` Jeff King
2018-12-26 22:29 ` Junio C Hamano
2019-01-15 19:59 ` [PATCH v5 " Josh Steadmon
2019-01-15 19:59 ` [PATCH v5 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2019-01-15 20:33 ` Junio C Hamano
2019-01-15 19:59 ` [PATCH v5 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2019-01-15 19:59 ` [PATCH v5 3/3] Makefile: correct example fuzz build Josh Steadmon
2019-01-15 20:39 ` Junio C Hamano
2019-01-15 21:59 ` Josh Steadmon
2019-01-15 22:34 ` Junio C Hamano
2019-01-15 22:25 ` [PATCH v6 0/3] Add commit-graph fuzzer and fix buffer overflow Josh Steadmon
2019-01-15 22:25 ` [PATCH v6 1/3] commit-graph, fuzz: Add fuzzer for commit-graph Josh Steadmon
2019-01-15 22:25 ` [PATCH v6 2/3] commit-graph: fix buffer read-overflow Josh Steadmon
2019-02-20 14:55 ` Ævar Arnfjörð Bjarmason
2019-02-20 16:50 ` SZEDER Gábor
2019-01-15 22:25 ` [PATCH v6 3/3] Makefile: correct example fuzz build Josh Steadmon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=80b5662f30cb87210385a6bd26e037ce39e46b6d.1544729841.git.steadmon@google.com \
--to=steadmon@google.com \
--cc=avarab@gmail.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=peff@peff.net \
--cc=stolee@gmail.com \
--cc=szeder.dev@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).