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Tue, 13 Oct 2026 13:22:12 -0700 (PDT) Received: from [127.0.0.1] ([20.15.229.147]) by smtp.gmail.com with ESMTPSA id 5614622812f47-518a72a6048sm9844967b6e.5.2026.10.13.13.22.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 13:22:12 -0700 (PDT) Message-Id: In-Reply-To: References: From: "Ravi Mistry via GitGitGadget" Date: Tue, 13 Oct 2026 20:22:07 +0000 Subject: [PATCH v6 1/2] blame: harden ignore-revs parser and tag peeling Fcc: Sent Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 To: git@vger.kernel.org Cc: Junio C Hamano , Abhijeetsingh Meena , Kristoffer Haugsbakk , Phillip Wood , Eric Sunshine , Phillip Wood , Ravi Mistry , Ravi Mistry From: Ravi Mistry Currently, blame.ignoreRevsFile and --ignore-revs-file only read paths explicitly configured by the user, which cannot point to an attacker-controlled file under Git's threat model. An upcoming commit will teach git-blame(1) and git-annotate(1) to automatically read .git-blame-ignore-revs by default if it exists, exposing the ignore-revs parser (oidset_parse_file_carefully() in oidset.c) and its tag-peeling callback (peel_to_commit_oid() in builtin/blame.c) to upstream-controlled content at a well-known path. Harden both code paths before enabling the default ignore-revs file: - In oidset_parse_file_carefully(), strbuf_getline() reads up to the next newline and records the full line length in sb.len, including any embedded NUL bytes. However, strchr(sb.buf, '#') and parse_oid_hex_algop(sb.buf, &oid, &p, algop) treat sb.buf as a NUL-terminated string. If a line contains an embedded NUL byte after a valid object name (such as "\0garbage" or "\0# comment"), *p is '\0' and trailing bytes on the line are silently ignored. Reject any line containing an embedded NUL byte via memchr() before stripping comments and whitespace. - In peel_to_commit_oid(), odb_read_object_info() is called without OBJECT_INFO_SKIP_FETCH_OBJECT or OBJECT_INFO_QUICK, and deref_tag() calls parse_object() on tag targets without checking whether the target object exists locally first. In a partial clone, any missing commit OID or tag target listed in the ignore-revs file would trigger lazy promisor fetches and pack directory rescans during git-blame(1). Use odb_read_object_info_extended() with OBJECT_INFO_LOOKUP_REPLACE | OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK and peel OBJ_TAG objects one layer per iteration, verifying that each target object exists locally and matches the tag's declared type before parsing it. Signed-off-by: Ravi Mistry --- builtin/blame.c | 20 +++++++++++++++++-- oidset.c | 3 +++ t/t8013-blame-ignore-revs.sh | 38 ++++++++++++++++++++++++++++++++++++ 3 files changed, 59 insertions(+), 2 deletions(-) diff --git a/builtin/blame.c b/builtin/blame.c index 48d5251c6d..6741a7b9df 100644 --- a/builtin/blame.c +++ b/builtin/blame.c @@ -911,21 +911,37 @@ static int is_a_rev(const char *name) static int peel_to_commit_oid(struct object_id *oid_ret, void *cbdata) { struct repository *r = ((struct blame_scoreboard *)cbdata)->repo; + enum object_type expected_type = OBJ_ANY; struct object_id oid; oidcpy(&oid, oid_ret); while (1) { + unsigned flags = OBJECT_INFO_LOOKUP_REPLACE | + OBJECT_INFO_SKIP_FETCH_OBJECT | + OBJECT_INFO_QUICK; + struct object_info oi = OBJECT_INFO_INIT; + enum object_type kind; struct object *obj; - int kind = odb_read_object_info(r->objects, &oid, NULL); + + oi.typep = &kind; + if (odb_read_object_info_extended(r->objects, &oid, &oi, + flags) < 0) + return -1; + if (expected_type != OBJ_ANY && kind != expected_type) + return -1; if (kind == OBJ_COMMIT) { oidcpy(oid_ret, &oid); return 0; } if (kind != OBJ_TAG) return -1; - obj = deref_tag(r, parse_object(r, &oid), NULL, 0); + obj = parse_object(r, &oid); + if (!obj || obj->type != OBJ_TAG) + return -1; + obj = ((struct tag *)obj)->tagged; if (!obj) return -1; + expected_type = obj->type; oidcpy(&oid, &obj->oid); } } diff --git a/oidset.c b/oidset.c index c8ff0b385c..90d39204d3 100644 --- a/oidset.c +++ b/oidset.c @@ -85,6 +85,9 @@ void oidset_parse_file_carefully(struct oidset *set, const char *path, const char *p; const char *name; + if (memchr(sb.buf, '\0', sb.len)) + die("invalid object name: %s", sb.buf); + /* * Allow trailing comments, leading whitespace * (including before commits), and empty or whitespace diff --git a/t/t8013-blame-ignore-revs.sh b/t/t8013-blame-ignore-revs.sh index cace00ae8d..70fe509a64 100755 --- a/t/t8013-blame-ignore-revs.sh +++ b/t/t8013-blame-ignore-revs.sh @@ -327,4 +327,42 @@ test_expect_success ignore_merge ' test_cmp expect actual ' +test_expect_success 'ignore-revs-file rejects lines with embedded NUL bytes' ' + rev_b=$(git rev-parse B) && + printf "%sQgarbage\n" "$rev_b" | q_to_nul >ignore_nul && + test_must_fail git blame file --ignore-revs-file ignore_nul 2>err && + test_grep "invalid object name:" err && + + printf "%sQ# comment\n" "$rev_b" | q_to_nul >ignore_nul_comment && + test_must_fail git blame file --ignore-revs-file ignore_nul_comment 2>err && + test_grep "invalid object name:" err +' + +test_expect_success 'ignore-revs-file peels chained tags and skips missing tag targets' ' + test_write_lines BB L2-modified L3 L4 L5 L6 L7 L8 CC >file && + git add file && + test_tick && + git commit -m D && + git tag -a -m "tag 1" D_TAG1 HEAD && + git tag -a -m "tag 2" D_TAG2 D_TAG1 && + git rev-parse D_TAG2 >ignore_tag_chain && + git blame --line-porcelain file --ignore-revs-file ignore_tag_chain >blame_raw && + sed -ne "/^[0-9a-f][0-9a-f]* [0-9][0-9]* 2/s/ .*//p" blame_raw >actual && + git rev-parse A >expect && + test_cmp expect actual && + + test_config extensions.partialClone origin && + test_config remote.origin.promisor true && + test_config remote.origin.url /nonexistent && + missing_oid=$(test_oid deadbeef) && + bad_tag=$(printf "object %s\ntype commit\ntag bad-tag\ntagger T 0 +0000\n\nmsg\n" "$missing_oid" | + git hash-object -t tag -w --stdin) && + test_write_lines "$missing_oid" "$bad_tag" >ignore_bad_tag && + git blame --line-porcelain file --ignore-revs-file ignore_bad_tag >blame_raw 2>err && + test_must_be_empty err && + sed -ne "/^[0-9a-f][0-9a-f]* [0-9][0-9]* 2/s/ .*//p" blame_raw >actual && + git rev-parse HEAD >expect && + test_cmp expect actual +' + test_done -- gitgitgadget