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From 81dc898df9b4b4035534a927f3234a3839b698bf Mon Sep 17 00:00:00 2001
From: Patrick Steinhardt <ps@pks.im>
Date: Thu, 1 Dec 2022 15:46:25 +0100
Subject: [PATCH 02/12] pretty: fix out-of-bounds write caused by integer overflow
When using a padding specifier in the pretty format passed to git-log(1)
we need to calculate the string length in several places. These string
lengths are stored in `int`s though, which means that these can easily
overflow when the input lengths exceeds 2GB. This can ultimately lead to
an out-of-bounds write when these are used in a call to memcpy(3P):
==8340==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x7f1ec62f97fe at pc 0x7f2127e5f427 bp 0x7ffd3bd63de0 sp 0x7ffd3bd63588
WRITE of size 1 at 0x7f1ec62f97fe thread T0
#0 0x7f2127e5f426 in __interceptor_memcpy /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827
#1 0x5628e96aa605 in format_and_pad_commit pretty.c:1762
#2 0x5628e96aa7f4 in format_commit_item pretty.c:1801
#3 0x5628e97cdb24 in strbuf_expand strbuf.c:429
#4 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
#5 0x5628e96acd0f in pretty_print_commit pretty.c:2161
#6 0x5628e95a44c8 in show_log log-tree.c:781
#7 0x5628e95a76ba in log_tree_commit log-tree.c:1117
#8 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
#9 0x5628e922c35b in cmd_log_walk builtin/log.c:549
#10 0x5628e922f1a2 in cmd_log builtin/log.c:883
#11 0x5628e9106993 in run_builtin git.c:466
#12 0x5628e9107397 in handle_builtin git.c:721
#13 0x5628e9107b07 in run_argv git.c:788
#14 0x5628e91088a7 in cmd_main git.c:923
#15 0x5628e939d682 in main common-main.c:57
#16 0x7f2127c3c28f (/usr/lib/libc.so.6+0x2328f)
#17 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
#18 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115
0x7f1ec62f97fe is located 2 bytes to the left of 4831838265-byte region [0x7f1ec62f9800,0x7f1fe62f9839)
allocated by thread T0 here:
#0 0x7f2127ebe7ea in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:85
#1 0x5628e98774d4 in xrealloc wrapper.c:136
#2 0x5628e97cb01c in strbuf_grow strbuf.c:99
#3 0x5628e97ccd42 in strbuf_addchars strbuf.c:327
#4 0x5628e96aa55c in format_and_pad_commit pretty.c:1761
#5 0x5628e96aa7f4 in format_commit_item pretty.c:1801
#6 0x5628e97cdb24 in strbuf_expand strbuf.c:429
#7 0x5628e96ab060 in repo_format_commit_message pretty.c:1869
#8 0x5628e96acd0f in pretty_print_commit pretty.c:2161
#9 0x5628e95a44c8 in show_log log-tree.c:781
#10 0x5628e95a76ba in log_tree_commit log-tree.c:1117
#11 0x5628e922bed5 in cmd_log_walk_no_free builtin/log.c:508
#12 0x5628e922c35b in cmd_log_walk builtin/log.c:549
#13 0x5628e922f1a2 in cmd_log builtin/log.c:883
#14 0x5628e9106993 in run_builtin git.c:466
#15 0x5628e9107397 in handle_builtin git.c:721
#16 0x5628e9107b07 in run_argv git.c:788
#17 0x5628e91088a7 in cmd_main git.c:923
#18 0x5628e939d682 in main common-main.c:57
#19 0x7f2127c3c28f (/usr/lib/libc.so.6+0x2328f)
#20 0x7f2127c3c349 in __libc_start_main (/usr/lib/libc.so.6+0x23349)
#21 0x5628e91020e4 in _start ../sysdeps/x86_64/start.S:115
SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/src/debug/gcc/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:827 in __interceptor_memcpy
Shadow bytes around the buggy address:
0x0fe458c572a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0fe458c572e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0fe458c572f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa[fa]
0x0fe458c57300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57310: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57320: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57330: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0fe458c57340: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==8340==ABORTING
The pretty format can also be used in `git archive` operations via the
`export-subst` attribute. So this is what in our opinion makes this a
critical issue in the context of Git forges which allow to download an
archive of user supplied Git repositories.
Fix this vulnerability by using `size_t` instead of `int` to track the
string lengths. Add tests which detect this vulnerability when Git is
compiled with the address sanitizer.
Reported-by: Joern Schneeweisz <jschneeweisz@gitlab.com>
Original-patch-by: Joern Schneeweisz <jschneeweisz@gitlab.com>
Modified-by: Taylor Blau <me@ttalorr.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Upstream-Status: Backport [https://github.com/git/git/commit/81dc898df9b4b4035534a927f3234a3839b698bf]
CVE: CVE-2022-41903
Signed-off-by: Vijay Anusuri <vanusuri@mvista.com>
---
pretty.c | 11 ++++++-----
t/t4205-log-pretty-formats.sh | 17 +++++++++++++++++
2 files changed, 23 insertions(+), 5 deletions(-)
diff --git a/pretty.c b/pretty.c
index b32f036..637e344 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1427,7 +1427,9 @@ static size_t format_and_pad_commit(struct strbuf *sb, /* in UTF-8 */
struct format_commit_context *c)
{
struct strbuf local_sb = STRBUF_INIT;
- int total_consumed = 0, len, padding = c->padding;
+ size_t total_consumed = 0;
+ int len, padding = c->padding;
+
if (padding < 0) {
const char *start = strrchr(sb->buf, '\n');
int occupied;
@@ -1439,7 +1441,7 @@ static size_t format_and_pad_commit(struct strbuf *sb, /* in UTF-8 */
}
while (1) {
int modifier = *placeholder == 'C';
- int consumed = format_commit_one(&local_sb, placeholder, c);
+ size_t consumed = format_commit_one(&local_sb, placeholder, c);
total_consumed += consumed;
if (!modifier)
@@ -1505,7 +1507,7 @@ static size_t format_and_pad_commit(struct strbuf *sb, /* in UTF-8 */
}
strbuf_addbuf(sb, &local_sb);
} else {
- int sb_len = sb->len, offset = 0;
+ size_t sb_len = sb->len, offset = 0;
if (c->flush_type == flush_left)
offset = padding - len;
else if (c->flush_type == flush_both)
@@ -1528,8 +1530,7 @@ static size_t format_commit_item(struct strbuf *sb, /* in UTF-8 */
const char *placeholder,
void *context)
{
- int consumed;
- size_t orig_len;
+ size_t consumed, orig_len;
enum {
NO_MAGIC,
ADD_LF_BEFORE_NON_EMPTY,
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index f42a69f..a2acee1 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -788,4 +788,21 @@ test_expect_success '%S in git log --format works with other placeholders (part
test_cmp expect actual
'
+test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'log --pretty with huge commit message' '
+ # We only assert that this command does not crash. This needs to be
+ # executed with the address sanitizer to demonstrate failure.
+ git log -1 --pretty="format:%>(2147483646)%x41%41%>(2147483646)%x41" >/dev/null
+'
+
+test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'set up huge commit' '
+ test-tool genzeros 2147483649 | tr "\000" "1" >expect &&
+ huge_commit=$(git commit-tree -F expect HEAD^{tree})
+'
+
+test_expect_success EXPENSIVE,SIZE_T_IS_64BIT 'log --pretty with huge commit message' '
+ git log -1 --format="%B%<(1)%x30" $huge_commit >actual &&
+ echo 0 >>expect &&
+ test_cmp expect actual
+'
+
test_done
--
2.25.1
|
