Merge branch '279-issue02-null-pointer-deref-epsonds_net_read' into 'master'

Resolve "memory corruption bugs in libsane"

See merge request sane-project/backends!500

backend/epsonds-net.c

@@ -32,11 +32,12 @@
 
 #include "sane/sanei_debug.h"
 
-static int
+static ssize_t
 epsonds_net_read_raw(epsonds_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;
 
@@ -62,106 +63,98 @@ epsonds_net_read_raw(epsonds_scanner *s, unsigned char *buf, ssize_t wanted,
 	return read;
 }
 
-int
+static ssize_t
+epsonds_net_read_buf(epsonds_scanner *s, unsigned char *buf, ssize_t wanted,
+		       SANE_Status * status)
+{
+	ssize_t read = 0;
+
+	DBG(23, "%s: reading up to %lu from buffer at %p, %lu available\n",
+		__func__, (u_long) wanted, s->netptr, (u_long) s->netlen);
+
+	if ((size_t) wanted > s->netlen) {
+		*status = SANE_STATUS_IO_ERROR;
+		wanted = s->netlen;
+	}
+
+	memcpy(buf, s->netptr, wanted);
+	read = wanted;
+
+	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
 epsonds_net_read(epsonds_scanner *s, unsigned char *buf, ssize_t wanted,
 		       SANE_Status * status)
 {
-	ssize_t size;
+	if (wanted < 0) {
-	ssize_t read = 0;
+		*status = SANE_STATUS_INVAL;
-	unsigned char header[12];
-
-	/* read from buffer, if available */
-	if (wanted && s->netptr != s->netbuf) {
-		DBG(23, "reading %lu from buffer at %p, %lu available\n",
-			(u_long) wanted, s->netptr, (u_long) s->netlen);
-
-		memcpy(buf, s->netptr, wanted);
-		read = wanted;
-
-		s->netlen -= 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;
-		}
-
-		return read;
-	}
-
-	/* receive net header */
-	size = epsonds_net_read_raw(s, header, 12, status);
-	if (size != 12) {
 		return 0;
 	}
 
+	size_t size;
+	ssize_t read = 0;
+	unsigned char header[12];
+
+	/* read from remainder of buffer */
+	if (s->netptr) {
+		return epsonds_net_read_buf(s, buf, wanted, status);
+	}
+
+	/* receive net header */
+	read = epsonds_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;
 	}
 
-	// incoming payload size
+	/* 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) {
+	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);
 
-		DBG(15, "%s: full read\n", __func__);
+		if ((size_t) wanted > size) {
-
+			wanted = size;
-		if (size) {
-			read = epsonds_net_read_raw(s, buf, size, status);
 		}
 
-		if (s->netbuf) {
+		read = epsonds_net_read_raw(s, buf, wanted, status);
-			free(s->netbuf);
-			s->netbuf = NULL;
-			s->netlen = 0;
-		}
-
-		if (read < 0) {
-			return 0;
-		}
-
-	} else if (wanted < size) {
-
-		DBG(23, "%s: long tail\n", __func__);
-
-		read = epsonds_net_read_raw(s, s->netbuf, size, status);
-		if (read != size) {
-			return 0;
-		}
-
-		memcpy(buf, s->netbuf, wanted);
-		read = wanted;
-
-		free(s->netbuf);
-		s->netbuf = NULL;
-		s->netlen = 0;
-
 	} else {
+		DBG(15, "%s: buffered read\n", __func__);
+		DBG(23, "%s: bufferable = %lu, available = %lu\n", __func__,
+			(u_long) s->netlen, (u_long) size);
 
-		DBG(23, "%s: partial read\n", __func__);
+		if (s->netlen > size) {
-
+			s->netlen = size;
-		read = epsonds_net_read_raw(s, s->netbuf, size, status);
-		if (read != size) {
-			return 0;
 		}
 
-		s->netlen = size - wanted;
+		/* fill buffer */
-		s->netptr += wanted;
+		read = epsonds_net_read_raw(s, s->netbuf, s->netlen, status);
-		read = wanted;
+		s->netptr = s->netbuf;
+		s->netlen = (read > 0 ? read : 0);
 
-		DBG(23, "0,4 %02x %02x\n", s->netbuf[0], s->netbuf[4]);
+		/* copy wanted part */
-		DBG(23, "storing %lu to buffer at %p, next read at %p, %lu bytes left\n",
+		read = epsonds_net_read_buf(s, buf, wanted, status);
-			(u_long) size, s->netbuf, s->netptr, (u_long) s->netlen);
-
-		memcpy(buf, s->netbuf, wanted);
 	}
 
 	return read;
@@ -175,23 +168,38 @@ epsonds_net_request_read(epsonds_scanner *s, size_t len)
 	return status;
 }
 
-int
+size_t
 epsonds_net_write(epsonds_scanner *s, unsigned int cmd, const unsigned char *buf,
 			size_t buf_size, size_t reply_len, SANE_Status *status)
 {
 	unsigned char *h1, *h2;
 	unsigned char *packet = malloc(12 + 8);
 
-	/* XXX check allocation failure */
+	if (!packet) {
+		*status = SANE_STATUS_NO_MEM;
+		return 0;
+	}
 
 	h1 = packet;		// packet header
 	h2 = packet + 12;	// data header
 
 	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",
+		DBG(24, "%s: allocated %lu bytes at %p\n", __func__,
-			(u_long) reply_len, s->netbuf);
+			(u_long) s->netlen, s->netbuf);
 	}
 
 	DBG(24, "%s: cmd = %04x, buf = %p, buf_size = %lu, reply_len = %lu\n",

backend/epsonds-net.h

@@ -4,9 +4,9 @@
 #include <sys/types.h>
 #include "../include/sane/sane.h"
 
-extern int epsonds_net_read(struct epsonds_scanner *s, unsigned char *buf, ssize_t buf_size,
+extern ssize_t epsonds_net_read(struct epsonds_scanner *s, unsigned char *buf, ssize_t buf_size,
 				SANE_Status *status);
-extern int epsonds_net_write(struct epsonds_scanner *s, unsigned int cmd, const unsigned char *buf,
+extern size_t epsonds_net_write(struct epsonds_scanner *s, unsigned int cmd, const unsigned char *buf,
 				size_t buf_size, size_t reply_len,
 				SANE_Status *status);
 extern SANE_Status epsonds_net_lock(struct epsonds_scanner *s);

backend/epsonds.c

@@ -247,8 +247,8 @@ open_scanner(epsonds_scanner *s)
 
 			/* the scanner sends a kind of welcome msg */
 			// XXX check command type, answer to connect is 0x80
-			read = eds_recv(s, buf, 3, &status);
+			read = eds_recv(s, buf, 5, &status);
-			if (read != 3) {
+			if (read != 5) {
 				sanei_tcp_close(s->fd);
 				s->fd = -1;
 				return SANE_STATUS_IO_ERROR;