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pkt-line: add size parameter to packet_length()

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hex2chr() takes care not to run over the end of a NUL-terminated string.
It's used in packet_length(), but both callers of that function pass a
four-byte buffer, making NUL-checks unnecessary.  packet_length() could
accidentally be used with a pointer to a buffer of unknown size at new
call-sites, though, and the compiler wouldn't complain.

Add a size parameter plus check, and remove the NUL-checks by calling
hexval() directly.  This trades three NUL checks against one size check
and the ability to report the use of a short buffer at runtime.

If any of the four bytes is NUL or -- more generally -- not a
hexadecimal digit, then packet_length() still returns a negative value.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
René Scharfe 2023-07-07 23:47:55 +02:00 committed by Junio C Hamano
parent fb7d80edca
commit 3e81b896f7
3 changed files with 11 additions and 6 deletions
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12
pkt-line.c
View File

@ -373,10 +373,14 @@ static int get_packet_data(int fd, char **src_buf, size_t *src_size,
return ret;
}
int packet_length(const char lenbuf_hex[4])
int packet_length(const char lenbuf_hex[4], size_t size)
{
int val = hex2chr(lenbuf_hex);
return (val < 0) ? val : (val << 8) | hex2chr(lenbuf_hex + 2);
if (size < 4)
BUG("buffer too small");
return hexval(lenbuf_hex[0]) << 12 |
hexval(lenbuf_hex[1]) << 8 |
hexval(lenbuf_hex[2]) << 4 |
hexval(lenbuf_hex[3]);
}
static char *find_packfile_uri_path(const char *buffer)
@ -419,7 +423,7 @@ enum packet_read_status packet_read_with_status(int fd, char **src_buffer,
return PACKET_READ_EOF;
}
len = packet_length(linelen);
len = packet_length(linelen, sizeof(linelen));
if (len < 0) {
if (options & PACKET_READ_GENTLE_ON_READ_ERROR)

2
pkt-line.h
View File

@ -94,7 +94,7 @@ int packet_read(int fd, char *buffer, unsigned size, int options);
* If lenbuf_hex contains non-hex characters, return -1. Otherwise, return the
* numeric value of the length header.
*/
int packet_length(const char lenbuf_hex[4]);
int packet_length(const char lenbuf_hex[4], size_t size);
/*
* Read a packetized line into a buffer like the 'packet_read()' function but

3
remote-curl.c
View File

@ -763,7 +763,8 @@ static void check_pktline(struct check_pktline_state *state, const char *ptr, si
size -= digits_remaining;
if (state->len_filled == 4) {
state->remaining = packet_length(state->len_buf);
state->remaining = packet_length(state->len_buf,
sizeof(state->len_buf));
if (state->remaining < 0) {
die(_("remote-curl: bad line length character: %.4s"), state->len_buf);
} else if (state->remaining == 2) {