load_sys(): Add a buffer size argument

This adds a buffer size argument to load_sys(), rather than relying on
a hard coded buffer size. The old behavior was safe because we knew
the kernel would never return strings overrunning the buffers, however
it was ugly, and would cause code checking tools to spit out warnings.

This caused a Coverity warning over the read into
sra->sysfs_array_state which is only 20 bytes.

Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>

1 files changed, 24 insertions, 23 deletions

diff --git a/sysfs.c b/sysfs.c
index 26003432..8379ca83 100644
--- a/sysfs.c
+++ b/sysfs.c
@@ -27,15 +27,15 @@
 #include	<dirent.h>
 #include	<ctype.h>
 
-int load_sys(char *path, char *buf)
+int load_sys(char *path, char *buf, int len)
 {
 	int fd = open(path, O_RDONLY);
 	int n;
 	if (fd < 0)
 		return -1;
-	n = read(fd, buf, 1024);
+	n = read(fd, buf, len);
 	close(fd);
-	if (n <0 || n >= 1024)
+	if (n <0 || n >= len)
 		return -1;
 	buf[n] = 0;
 	if (n && buf[n-1] == '\n')
@@ -118,7 +118,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 	sra->devs = NULL;
 	if (options & GET_VERSION) {
 		strcpy(base, "metadata_version");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		if (strncmp(buf, "none", 4) == 0) {
 			sra->array.major_version =
@@ -137,31 +137,31 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 	}
 	if (options & GET_LEVEL) {
 		strcpy(base, "level");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->array.level = map_name(pers, buf);
 	}
 	if (options & GET_LAYOUT) {
 		strcpy(base, "layout");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->array.layout = strtoul(buf, NULL, 0);
 	}
 	if (options & GET_DISKS) {
 		strcpy(base, "raid_disks");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->array.raid_disks = strtoul(buf, NULL, 0);
 	}
 	if (options & GET_DEGRADED) {
 		strcpy(base, "degraded");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->array.failed_disks = strtoul(buf, NULL, 0);
 	}
 	if (options & GET_COMPONENT) {
 		strcpy(base, "component_size");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->component_size = strtoull(buf, NULL, 0);
 		/* sysfs reports "K", but we want sectors */
@@ -169,13 +169,13 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 	}
 	if (options & GET_CHUNK) {
 		strcpy(base, "chunk_size");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->array.chunk_size = strtoul(buf, NULL, 0);
 	}
 	if (options & GET_CACHE) {
 		strcpy(base, "stripe_cache_size");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			/* Probably level doesn't support it */
 			sra->cache_size = 0;
 		else
@@ -183,7 +183,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 	}
 	if (options & GET_MISMATCH) {
 		strcpy(base, "mismatch_cnt");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		sra->mismatch_cnt = strtoul(buf, NULL, 0);
 	}
@@ -195,7 +195,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 		size_t len;
 
 		strcpy(base, "safe_mode_delay");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 
 		/* remove a period, and count digits after it */
@@ -218,7 +218,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 	}
 	if (options & GET_BITMAP_LOCATION) {
 		strcpy(base, "bitmap/location");
-		if (load_sys(fname, buf))
+		if (load_sys(fname, buf, sizeof(buf)))
 			goto abort;
 		if (strncmp(buf, "file", 4) == 0)
 			sra->bitmap_offset = 1;
@@ -232,7 +232,8 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 
 	if (options & GET_ARRAY_STATE) {
 		strcpy(base, "array_state");
-		if (load_sys(fname, sra->sysfs_array_state))
+		if (load_sys(fname, sra->sysfs_array_state,
+			     sizeof(sra->sysfs_array_state)))
 			goto abort;
 	} else
 		sra->sysfs_array_state[0] = 0;
@@ -262,7 +263,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 
 		/* Always get slot, major, minor */
 		strcpy(dbase, "slot");
-		if (load_sys(fname, buf)) {
+		if (load_sys(fname, buf, sizeof(buf))) {
 			/* hmm... unable to read 'slot' maybe the device
 			 * is going away?
 			 */
@@ -287,7 +288,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 		if (*ep) dev->disk.raid_disk = -1;
 
 		strcpy(dbase, "block/dev");
-		if (load_sys(fname, buf)) {
+		if (load_sys(fname, buf, sizeof(buf))) {
 			/* assume this is a stale reference to a hot
 			 * removed device
 			 */
@@ -299,7 +300,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 
 		/* special case check for block devices that can go 'offline' */
 		strcpy(dbase, "block/device/state");
-		if (load_sys(fname, buf) == 0 &&
+		if (load_sys(fname, buf, sizeof(buf)) == 0 &&
 		    strncmp(buf, "offline", 7) == 0) {
 			free(dev);
 			continue;
@@ -312,25 +313,25 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 
 		if (options & GET_OFFSET) {
 			strcpy(dbase, "offset");
-			if (load_sys(fname, buf))
+			if (load_sys(fname, buf, sizeof(buf)))
 				goto abort;
 			dev->data_offset = strtoull(buf, NULL, 0);
 			strcpy(dbase, "new_offset");
-			if (load_sys(fname, buf) == 0)
+			if (load_sys(fname, buf, sizeof(buf)) == 0)
 				dev->new_data_offset = strtoull(buf, NULL, 0);
 			else
 				dev->new_data_offset = dev->data_offset;
 		}
 		if (options & GET_SIZE) {
 			strcpy(dbase, "size");
-			if (load_sys(fname, buf))
+			if (load_sys(fname, buf, sizeof(buf)))
 				goto abort;
 			dev->component_size = strtoull(buf, NULL, 0) * 2;
 		}
 		if (options & GET_STATE) {
 			dev->disk.state = 0;
 			strcpy(dbase, "state");
-			if (load_sys(fname, buf))
+			if (load_sys(fname, buf, sizeof(buf)))
 				goto abort;
 			if (strstr(buf, "in_sync"))
 				dev->disk.state |= (1<<MD_DISK_SYNC);
@@ -341,7 +342,7 @@ struct mdinfo *sysfs_read(int fd, char *devnm, unsigned long options)
 		}
 		if (options & GET_ERROR) {
 			strcpy(buf, "errors");
-			if (load_sys(fname, buf))
+			if (load_sys(fname, buf, sizeof(buf)))
 				goto abort;
 			dev->errors = strtoul(buf, NULL, 0);
 		}