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commit: reject overlong UTF-8 sequences

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The commit code accepts pseudo-UTF-8 sequences that encode a character with more
bytes than necessary.  Reject such sequences, since they are not valid UTF-8.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
brian m. carlson
2013-07-04 17:20:34 +00:00
committed by Junio C Hamano
parent 28110d4bfc
commit e82bd6cc70
2 changed files with 22 additions and 6 deletions
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18
commit.c
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@ -1240,11 +1240,15 @@ int commit_tree(const struct strbuf *msg, unsigned char *tree,
static int find_invalid_utf8(const char *buf, int len)
{
int offset = 0;
static const unsigned int max_codepoint[] = {
0x7f, 0x7ff, 0xffff, 0x10ffff
};
while (len) {
unsigned char c = *buf++;
int bytes, bad_offset;
unsigned int codepoint;
unsigned int min_val, max_val;
len--;
offset++;
@ -1276,8 +1280,13 @@ static int find_invalid_utf8(const char *buf, int len)
if (len < bytes)
return bad_offset;
/* Place the encoded bits at the bottom of the value. */
/*
* Place the encoded bits at the bottom of the value and compute the
* valid range.
*/
codepoint = (c & 0x7f) >> bytes;
min_val = max_codepoint[bytes-1] + 1;
max_val = max_codepoint[bytes];
offset += bytes;
len -= bytes;
@ -1290,8 +1299,8 @@ static int find_invalid_utf8(const char *buf, int len)
return bad_offset;
} while (--bytes);
/* No codepoints can ever be allocated beyond U+10FFFF. */
if (codepoint > 0x10ffff)
/* Reject codepoints that are out of range for the sequence length. */
if (codepoint < min_val || codepoint > max_val)
return bad_offset;
/* Surrogates are only for UTF-16 and cannot be encoded in UTF-8. */
if ((codepoint & 0x1ff800) == 0xd800)
@ -1308,9 +1317,6 @@ static int find_invalid_utf8(const char *buf, int len)
*
* If it isn't, it assumes any non-utf8 characters are Latin1,
* and does the conversion.
*
* Fixme: we should probably also disallow overlong forms.
* But we don't do that currently.
*/
static int verify_utf8(struct strbuf *buf)
{