Re: [PATCH 1/2] sequencer: fix "rebase -i --root" corrupting author header
flat view
From: Johannes Schindelin <hidden>
Date: 2018-07-30 15:44:40
Hi Eric, On Mon, 30 Jul 2018, Eric Sunshine wrote:
When "git rebase -i --root" creates a new root commit (say, by swapping
in a different commit for the root), it corrupts the commit's "author"
header with trailing garbage:
author A U Thor [off-list ref] @1112912773 -07000or@example.com
This is a result of read_author_ident() neglecting to NUL-terminate the
buffer into which it composes the "author" header.
(Note that the extra "0" in the timezone is a separate bug which will be
fixed subsequently.)
Security considerations: Construction of the "author" header by
read_author_ident() happens in-place and in parallel with parsing the
content of "rebase-merge/author-script" which occupies the same buffer.
This is possible because the constructed "author" header is always
smaller than the content of "rebase-merge/author-script". Despite
neglecting to NUL-terminate the constructed "author" header, memory is
never accessed (either by read_author_ident() or its caller) beyond the
allocated buffer since a NUL-terminator is present at the end of the
loaded "rebase-merge/author-script" content, and additional NUL's are
inserted as part of the parsing process.
Signed-off-by: Eric Sunshine <redacted>ACK! Thanks, Dscho
quoted hunk ↗ jump to hunk
--- sequencer.c | 2 +- t/t3404-rebase-interactive.sh | 10 +++++++++- 2 files changed, 10 insertions(+), 2 deletions(-)diff --git a/sequencer.c b/sequencer.c index 16c1411054..78864d9072 100644 --- a/sequencer.c +++ b/sequencer.c@@ -744,7 +744,7 @@ static const char *read_author_ident(struct strbuf *buf) return NULL; } - buf->len = out - buf->buf; + strbuf_setlen(buf, out - buf->buf); return buf->buf; }diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh index 01616901bd..8509c89a26 100755 --- a/t/t3404-rebase-interactive.sh +++ b/t/t3404-rebase-interactive.sh@@ -1238,7 +1238,7 @@ rebase_setup_and_clean () { test_might_fail git branch -D $1 && test_might_fail git rebase --abort " && - git checkout -b $1 master + git checkout -b $1 ${2:-master} } test_expect_success 'drop' '@@ -1415,4 +1415,12 @@ test_expect_success 'rebase -i --gpg-sign=<key-id> overrides commit.gpgSign' ' test_i18ngrep "$SQ-S\"S I Gner\"$SQ" err ' +test_expect_success 'valid author header after --root swap' ' + rebase_setup_and_clean author-header no-conflict-branch && + set_fake_editor && + FAKE_LINES="2 1" git rebase -i --root && + git cat-file commit HEAD^ >out && + grep "^author ..* @[0-9][0-9]* [-+][0-9][0-9]*$" out +' + test_done-- 2.18.0.597.ga71716f1ad