libblkid-tiny: fix buffer overflow

Copying device name into a fixed-length buffer is problematic as
the name can be longer than the buffer, resulting in subsequent fields
getting corrupted and potentially even worse things.
Drop strcpy of device name and use of the copied value as it is known
anyway.

Before this fix:
/dev/mapper/owrt--volumes--e093cc66-rw_test: UUID="c66-rw_test" LABEL="test" VERSION="1.14" TYPE="f2fs"

After this fix:
/dev/mapper/owrt--volumes--e093cc66-rw_test: UUID="5eda3e52-3427-493a-a6d6-ffdb5a5836fd" LABEL="test" VERSION="1.14" TYPE="f2fs"

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

libblkid-tiny/libblkid-tiny.c

@@ -226,7 +226,6 @@ int probe_block(char *block, struct blkid_struct_probe *pr)
 			DEBUG("probing %s\n", idinfos[i]->name);
 			pr->err = idinfos[i]->probefunc(pr, mag);
 			pr->id = idinfos[i];
-			strcpy(pr->dev, block);
 			if (!pr->err)
 				break;
 		}

probe.c

@@ -31,16 +31,14 @@ probe_path_tiny(const char *path)
 	if (probe_block((char *)path, pr) == 0 && pr->id && !pr->err) {
 		info = calloc_a(sizeof(*info),
 		                &type,    strlen(pr->id->name) + 1,
-		                &dev,     strlen(pr->dev)      + 1,
+		                &dev,     strlen(path)         + 1,
 		                &uuid,    strlen(pr->uuid)     + 1,
 		                &label,   strlen(pr->label)    + 1,
 		                &version, strlen(pr->version)  + 1);
 
 		if (info) {
 			info->type = strcpy(type, pr->id->name);
-
-			if (pr->dev[0])
-				info->dev = strcpy(dev, pr->dev);
+			info->dev = strcpy(dev, path);
 
 			if (pr->uuid[0])
 				info->uuid = strcpy(uuid, pr->uuid);