blkid: linux_raid - fix logic for volumes with size == 0

 Based on

    commit 7643819062985d9fc6c7664072576e71d3822b10
    Author: Kay Sievers <kay.sievers@vrfy.org>
    Date:   Sat Sep 6 16:23:21 2008 +0200

 from udev upstream tree.

Reported-by: Scott James Remnant <scott@ubuntu.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

2 files changed, 25 insertions, 16 deletions

diff --git a/libs/blkid/src/probe.c b/libs/blkid/src/probe.c
index e6038c20..0e4745ac 100644
--- a/libs/blkid/src/probe.c
+++ b/libs/blkid/src/probe.c
@@ -196,6 +196,11 @@ unsigned char *blkid_probe_get_buffer(blkid_probe pr,
 {
 	ssize_t ret_read = 0;
 
+	if (off < 0 || len < 0) {
+		DBG(DEBUG_LOWPROBE,
+			printf("unexpected offset or length of buffer requested\n"));
+		return NULL;
+	}
 	if (off + len <= BLKID_SB_BUFSIZ) {
 		if (!pr->sbbuf) {
 			pr->sbbuf = malloc(BLKID_SB_BUFSIZ);
diff --git a/libs/blkid/src/probers/linux_raid.c b/libs/blkid/src/probers/linux_raid.c
index e21ac0a7..a5926561 100644
--- a/libs/blkid/src/probers/linux_raid.c
+++ b/libs/blkid/src/probers/linux_raid.c
@@ -125,25 +125,29 @@ static int probe_raid1(blkid_probe pr, off_t off)
 int probe_raid(blkid_probe pr, const struct blkid_idmag *mag)
 {
 	const char *ver = NULL;
-	uint64_t sboff;
 
-	/* version 0 at the end of the device */
-	sboff = (pr->size & ~(MD_RESERVED_BYTES - 1)) - MD_RESERVED_BYTES;
-	if (probe_raid0(pr, sboff) == 0)
-		return 0;
-
-	/* version 1.0 at the end of the device */
-	sboff = (pr->size & ~(0x1000 - 1)) - 0x2000;
-	if (probe_raid1(pr, sboff) == 0)
-		ver = "1.0";
+	if (pr->size > MD_RESERVED_BYTES) {
+		/* version 0 at the end of the device */
+		uint64_t sboff = (pr->size & ~(MD_RESERVED_BYTES - 1))
+			         - MD_RESERVED_BYTES;
+		if (probe_raid0(pr, sboff) == 0)
+			return 0;
+
+		/* version 1.0 at the end of the device */
+		sboff = (pr->size & ~(0x1000 - 1)) - 0x2000;
+		if (probe_raid1(pr, sboff) == 0)
+			ver = "1.0";
+	}
 
-	/* version 1.1 at the start of the device */
-	else if (probe_raid1(pr, 0) == 0)
-		ver = "1.1";
+	if (!ver) {
+		/* version 1.1 at the start of the device */
+		if (probe_raid1(pr, 0) == 0)
+			ver = "1.1";
 
-	/* version 1.2 at 4k offset from the start */
-	else if (probe_raid1(pr, 0x1000) == 0)
-		ver = "1.2";
+		/* version 1.2 at 4k offset from the start */
+		else if (probe_raid1(pr, 0x1000) == 0)
+			ver = "1.2";
+	}
 
 	if (ver) {
 		blkid_probe_set_version(pr, ver);