parse_commit_buffer: tighten checks while parsing
This tightens the parsing of a commit object in a couple of ways.
- The "tree " header must end with a LF (earlier we did not
check this condition).
- Make sure parsing of timestamp on the "committer " header
does not go beyond the buffer, even when (1) the "author "
header does not end with a LF (this means that the commit
object is malformed and lacks the committer information) or
(2) the "committer " header does not have ">" that is the end
of the e-mail address, or (3) the "committer " header does
not end with a LF.
We however still keep the existing behaviour to return a parsed
commit object even when non-structural headers such as committer
and author are malformed, so that tools that need to look at
commits to clean up a history with such broken commits can still
get at the structural data (i.e. the parents chain and the tree
object).
Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/commit.c b/commit.c
index f074811..8b8fb04 100644
--- a/commit.c
+++ b/commit.c
@@ -48,19 +48,32 @@
return check_commit(obj, sha1, 0);
}
-static unsigned long parse_commit_date(const char *buf)
+static unsigned long parse_commit_date(const char *buf, const char *tail)
{
unsigned long date;
+ const char *dateptr;
+ if (buf + 6 >= tail)
+ return 0;
if (memcmp(buf, "author", 6))
return 0;
- while (*buf++ != '\n')
+ while (buf < tail && *buf++ != '\n')
/* nada */;
+ if (buf + 9 >= tail)
+ return 0;
if (memcmp(buf, "committer", 9))
return 0;
- while (*buf++ != '>')
+ while (buf < tail && *buf++ != '>')
/* nada */;
- date = strtoul(buf, NULL, 10);
+ if (buf >= tail)
+ return 0;
+ dateptr = buf;
+ while (buf < tail && *buf++ != '\n')
+ /* nada */;
+ if (buf >= tail)
+ return 0;
+ /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
+ date = strtoul(dateptr, NULL, 10);
if (date == ULONG_MAX)
date = 0;
return date;
@@ -236,9 +249,9 @@
return 0;
item->object.parsed = 1;
tail += size;
- if (tail <= bufptr + 5 || memcmp(bufptr, "tree ", 5))
+ if (tail <= bufptr + 46 || memcmp(bufptr, "tree ", 5) || bufptr[45] != '\n')
return error("bogus commit object %s", sha1_to_hex(item->object.sha1));
- if (tail <= bufptr + 45 || get_sha1_hex(bufptr + 5, parent) < 0)
+ if (get_sha1_hex(bufptr + 5, parent) < 0)
return error("bad tree pointer in commit %s",
sha1_to_hex(item->object.sha1));
item->tree = lookup_tree(parent);
@@ -275,7 +288,7 @@
n_refs++;
}
}
- item->date = parse_commit_date(bufptr);
+ item->date = parse_commit_date(bufptr, tail);
if (track_object_refs) {
unsigned i = 0;
