Commit fff83e7e authored by Olaf Meeuwissen's avatar Olaf Meeuwissen

epson2: Rewrite network I/O

This addresses GHSL-2020-075 as well as all other problematic code
uncovered as a result of investigating that.  This includes:

- buffer overflows due to use of unchecked lengths
- integer overflows due to type conversions
- potential memory leaks
- checking for memory allocation failures

Re #279.
parent e52a5bf7
......@@ -32,11 +32,12 @@
#include "sane/sanei_debug.h"
static int
static ssize_t
sanei_epson_net_read_raw(Epson_Scanner *s, unsigned char *buf, ssize_t wanted,
SANE_Status *status)
{
int ready, read = -1;
int ready;
ssize_t read = -1;
fd_set readable;
struct timeval tv;
......@@ -62,111 +63,136 @@ sanei_epson_net_read_raw(Epson_Scanner *s, unsigned char *buf, ssize_t wanted,
return read;
}
int
sanei_epson_net_read(Epson_Scanner *s, unsigned char *buf, ssize_t wanted,
static ssize_t
sanei_epson_net_read_buf(Epson_Scanner *s, unsigned char *buf, ssize_t wanted,
SANE_Status * status)
{
ssize_t size;
ssize_t read = 0;
unsigned char header[12];
/* read from buffer, if available */
if (s->netptr != s->netbuf) {
DBG(23, "reading %lu from buffer at %p, %lu available\n",
(u_long) wanted, s->netptr, (u_long) s->netlen);
DBG(23, "%s: reading up to %lu from buffer at %p, %lu available\n",
__func__, (u_long) wanted, s->netptr, (u_long) s->netlen);
memcpy(buf, s->netptr, wanted);
read = wanted;
if ((size_t) wanted > s->netlen) {
*status = SANE_STATUS_IO_ERROR;
wanted = s->netlen;
}
s->netlen -= wanted;
memcpy(buf, s->netptr, wanted);
read = wanted;
if (s->netlen == 0) {
DBG(23, "%s: freeing %p\n", __func__, s->netbuf);
free(s->netbuf);
s->netbuf = s->netptr = NULL;
s->netlen = 0;
}
s->netptr += read;
s->netlen -= read;
if (s->netlen == 0) {
DBG(23, "%s: freeing %p\n", __func__, s->netbuf);
free(s->netbuf);
s->netbuf = s->netptr = NULL;
s->netlen = 0;
}
return read;
}
ssize_t
sanei_epson_net_read(Epson_Scanner *s, unsigned char *buf, ssize_t wanted,
SANE_Status * status)
{
if (wanted < 0) {
*status = SANE_STATUS_INVAL;
return 0;
}
size_t size;
ssize_t read = 0;
unsigned char header[12];
return read;
/* read from remainder of buffer */
if (s->netptr) {
return sanei_epson_net_read_buf(s, buf, wanted, status);
}
/* receive net header */
size = sanei_epson_net_read_raw(s, header, 12, status);
if (size != 12) {
read = sanei_epson_net_read_raw(s, header, 12, status);
if (read != 12) {
return 0;
}
/* validate header */
if (header[0] != 'I' || header[1] != 'S') {
DBG(1, "header mismatch: %02X %02x\n", header[0], header[1]);
*status = SANE_STATUS_IO_ERROR;
return 0;
}
/* parse payload size */
size = be32atoh(&header[6]);
DBG(23, "%s: wanted = %lu, available = %lu\n", __func__,
(u_long) wanted, (u_long) size);
*status = SANE_STATUS_GOOD;
if (size == wanted) {
DBG(15, "%s: full read\n", __func__);
read = sanei_epson_net_read_raw(s, buf, size, status);
if (!s->netbuf) {
DBG(15, "%s: direct read\n", __func__);
DBG(23, "%s: wanted = %lu, available = %lu\n", __func__,
(u_long) wanted, (u_long) size);
if (s->netbuf) {
free(s->netbuf);
s->netbuf = NULL;
s->netlen = 0;
if ((size_t) wanted > size) {
wanted = size;
}
if (read < 0) {
return 0;
}
/* } else if (wanted < size && s->netlen == size) { */
read = sanei_epson_net_read_raw(s, buf, wanted, status);
} else {
DBG(23, "%s: partial read\n", __func__);
DBG(15, "%s: buffered read\n", __func__);
DBG(23, "%s: bufferable = %lu, available = %lu\n", __func__,
(u_long) s->netlen, (u_long) size);
read = sanei_epson_net_read_raw(s, s->netbuf, size, status);
if (read != size) {
return 0;
if (s->netlen > size) {
s->netlen = size;
}
s->netlen = size - wanted;
s->netptr += wanted;
read = wanted;
DBG(23, "0,4 %02x %02x\n", s->netbuf[0], s->netbuf[4]);
DBG(23, "storing %lu to buffer at %p, next read at %p, %lu bytes left\n",
(u_long) size, s->netbuf, s->netptr, (u_long) s->netlen);
/* fill buffer */
read = sanei_epson_net_read_raw(s, s->netbuf, s->netlen, status);
s->netptr = s->netbuf;
s->netlen = (read > 0 ? read : 0);
memcpy(buf, s->netbuf, wanted);
/* copy wanted part */
read = sanei_epson_net_read_buf(s, buf, wanted, status);
}
return read;
}
int
size_t
sanei_epson_net_write(Epson_Scanner *s, unsigned int cmd, const unsigned char *buf,
size_t buf_size, size_t reply_len, SANE_Status *status)
{
unsigned char *h1, *h2, *payload;
unsigned char *packet = malloc(12 + 8 + buf_size);
/* XXX check allocation failure */
if (!packet) {
*status = SANE_STATUS_NO_MEM;
return 0;
}
h1 = packet;
h2 = packet + 12;
payload = packet + 12 + 8;
if (reply_len) {
s->netbuf = s->netptr = malloc(reply_len);
if (s->netbuf) {
DBG(23, "%s, freeing %p, %ld bytes unprocessed\n",
__func__, s->netbuf, (u_long) s->netlen);
free(s->netbuf);
s->netbuf = s->netptr = NULL;
s->netlen = 0;
}
s->netbuf = malloc(reply_len);
if (!s->netbuf) {
free(packet);
*status = SANE_STATUS_NO_MEM;
return 0;
}
s->netlen = reply_len;
DBG(24, "allocated %lu bytes at %p\n",
(u_long) reply_len, s->netbuf);
DBG(24, "%s: allocated %lu bytes at %p\n", __func__,
(u_long) s->netlen, s->netbuf);
}
DBG(24, "%s: cmd = %04x, buf = %p, buf_size = %lu, reply_len = %lu\n",
......
......@@ -4,9 +4,9 @@
#include <sys/types.h>
#include "../include/sane/sane.h"
extern int sanei_epson_net_read(struct Epson_Scanner *s, unsigned char *buf, ssize_t buf_size,
extern ssize_t sanei_epson_net_read(struct Epson_Scanner *s, unsigned char *buf, ssize_t buf_size,
SANE_Status *status);
extern int sanei_epson_net_write(struct Epson_Scanner *s, unsigned int cmd, const unsigned char *buf,
extern size_t sanei_epson_net_write(struct Epson_Scanner *s, unsigned int cmd, const unsigned char *buf,
size_t buf_size, size_t reply_len,
SANE_Status *status);
extern SANE_Status sanei_epson_net_lock(struct Epson_Scanner *s);
......
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