From: Karel Zak <kzak@redhat.com>
Date: Mon, 14 Jul 2014 12:53:41 +0000 (+0200)
Subject: libfdisk: make first sector buffer usage more robust
X-Git-Tag: v2.25~82
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7c2cfb18964b00881e65c461742af9038bd5b287;p=thirdparty%2Futil-linux.git

libfdisk: make first sector buffer usage more robust

	$ ~/util-linux/fdisk -b 4096 xxx
	..
	Segmentation fault

The buffer has to be reinitialized always when we apply a new
device properties (e.g. sector size).

Reported-by: Bernhard Voelker <mail@bernhard-voelker.de>
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libfdisk/src/alignment.c b/libfdisk/src/alignment.c
index a456b98b5c..65b2c4a23f 100644
--- a/libfdisk/src/alignment.c
+++ b/libfdisk/src/alignment.c
@@ -239,6 +239,8 @@ int fdisk_apply_user_device_properties(struct fdisk_context *cxt)
 		recount_geometry(cxt);
 
 	fdisk_reset_alignment(cxt);
+	if (cxt->firstsector_bufsz != cxt->sector_size)
+		fdisk_read_firstsector(cxt);
 
 	DBG(CXT, ul_debugobj(cxt, "new C/H/S: %u/%u/%u",
 		(unsigned) cxt->geom.cylinders,
@@ -484,9 +486,8 @@ int fdisk_reset_alignment(struct fdisk_context *cxt)
 	if (cxt->label && cxt->label->op->reset_alignment)
 		rc = cxt->label->op->reset_alignment(cxt);
 
-	DBG(CXT, ul_debugobj(cxt, "%s alignment reseted to: "
+	DBG(CXT, ul_debugobj(cxt, "alignment reseted to: "
 			    "first LBA=%ju, last LBA=%ju, grain=%lu [rc=%d]",
-			    cxt->label ? cxt->label->name : NULL,
 			    (uintmax_t) cxt->first_lba, (uintmax_t) cxt->last_lba,
 			    cxt->grain,	rc));
 	return rc;
diff --git a/libfdisk/src/context.c b/libfdisk/src/context.c
index 5fc4c6526b..2e224b363e 100644
--- a/libfdisk/src/context.c
+++ b/libfdisk/src/context.c
@@ -180,6 +180,7 @@ static void reset_context(struct fdisk_context *cxt)
 	cxt->dev_fd = -1;
 	cxt->dev_path = NULL;
 	cxt->firstsector = NULL;
+	cxt->firstsector_bufsz = 0;
 
 	fdisk_zeroize_device_properties(cxt);
 
diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index 5453eb3d76..e23abbbe8b 100644
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -586,6 +586,7 @@ static int dos_get_disklabel_id(struct fdisk_context *cxt, char **id)
 static int dos_create_disklabel(struct fdisk_context *cxt)
 {
 	unsigned int id;
+	int rc;
 
 	assert(cxt);
 	assert(cxt->label);
@@ -597,7 +598,9 @@ static int dos_create_disklabel(struct fdisk_context *cxt)
 	random_get_bytes(&id, sizeof(id));
 
 	dos_init(cxt);
-	fdisk_zeroize_firstsector(cxt);
+	rc = fdisk_init_firstsector_buffer(cxt);
+	if (rc)
+		return rc;
 	fdisk_label_set_changed(cxt->label, 1);
 
 	/* Generate an MBR ID for this disk */
diff --git a/libfdisk/src/fdiskP.h b/libfdisk/src/fdiskP.h
index f5b4bb8edb..ea6e291b1c 100644
--- a/libfdisk/src/fdiskP.h
+++ b/libfdisk/src/fdiskP.h
@@ -338,7 +338,9 @@ struct fdisk_ask {
 struct fdisk_context {
 	int dev_fd;         /* device descriptor */
 	char *dev_path;     /* device path */
+
 	unsigned char *firstsector; /* buffer with master boot record */
+	unsigned long firstsector_bufsz;
 
 	/* topology */
 	unsigned long io_size;		/* I/O size used by fdisk */
@@ -418,7 +420,7 @@ extern int fdisk_apply_user_device_properties(struct fdisk_context *cxt);
 extern void fdisk_zeroize_device_properties(struct fdisk_context *cxt);
 
 /* utils.c */
-extern void fdisk_zeroize_firstsector(struct fdisk_context *cxt);
+extern int fdisk_init_firstsector_buffer(struct fdisk_context *cxt);
 extern int fdisk_read_firstsector(struct fdisk_context *cxt);
 extern char *fdisk_partname(const char *dev, size_t partno);
 
diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
index 1ee1b49a23..db8651f46b 100644
--- a/libfdisk/src/gpt.c
+++ b/libfdisk/src/gpt.c
@@ -360,11 +360,14 @@ static inline int partition_unused(const struct gpt_entry *e)
 static int gpt_mknew_pmbr(struct fdisk_context *cxt)
 {
 	struct gpt_legacy_mbr *pmbr = NULL;
+	int rc;
 
 	if (!cxt || !cxt->firstsector)
 		return -ENOSYS;
 
-	fdisk_zeroize_firstsector(cxt);
+	rc = fdisk_init_firstsector_buffer(cxt);
+	if (rc)
+		return rc;
 
 	pmbr = (struct gpt_legacy_mbr *) cxt->firstsector;
 
diff --git a/libfdisk/src/sgi.c b/libfdisk/src/sgi.c
index cd12d80492..cf1354132a 100644
--- a/libfdisk/src/sgi.c
+++ b/libfdisk/src/sgi.c
@@ -908,6 +908,7 @@ static int sgi_create_disklabel(struct fdisk_context *cxt)
 {
 	struct fdisk_sgi_label *sgi;
 	struct sgi_disklabel *sgilabel;
+	int rc;
 
 	assert(cxt);
 	assert(cxt->label);
@@ -936,7 +937,10 @@ static int sgi_create_disklabel(struct fdisk_context *cxt)
 		}
 	}
 #endif
-	fdisk_zeroize_firstsector(cxt);
+	rc = fdisk_init_firstsector_buffer(cxt);
+	if (rc)
+		return rc;
+
 	sgi = (struct fdisk_sgi_label *) cxt->label;
 	sgi->header = (struct sgi_disklabel *) cxt->firstsector;
 
diff --git a/libfdisk/src/sun.c b/libfdisk/src/sun.c
index 734f5cd7d7..50bdf8668a 100644
--- a/libfdisk/src/sun.c
+++ b/libfdisk/src/sun.c
@@ -195,13 +195,17 @@ static int sun_create_disklabel(struct fdisk_context *cxt)
 	unsigned int ndiv;
 	struct fdisk_sun_label *sun;		/* libfdisk sun handler */
 	struct sun_disklabel *sunlabel;	/* on disk data */
+	int rc = 0;
 
 	assert(cxt);
 	assert(cxt->label);
 	assert(fdisk_is_disklabel(cxt, SUN));
 
 	/* map first sector to header */
-	fdisk_zeroize_firstsector(cxt);
+	rc = fdisk_init_firstsector_buffer(cxt);
+	if (rc)
+		return rc;
+
 	sun = (struct fdisk_sun_label *) cxt->label;
 	sun->header = (struct sun_disklabel *) cxt->firstsector;
 
diff --git a/libfdisk/src/utils.c b/libfdisk/src/utils.c
index 65abfbc1cb..e809c6e4ff 100644
--- a/libfdisk/src/utils.c
+++ b/libfdisk/src/utils.c
@@ -4,35 +4,50 @@
 
 #include <ctype.h>
 
-
 /*
  * Zeros in-memory first sector buffer
  */
-void fdisk_zeroize_firstsector(struct fdisk_context *cxt)
+int fdisk_init_firstsector_buffer(struct fdisk_context *cxt)
 {
-	if (!cxt || !cxt->firstsector)
-		return;
+	if (!cxt)
+		return -EINVAL;
+
+	if (!cxt->firstsector || cxt->firstsector_bufsz != cxt->sector_size) {
+		/* Let's allocate a new buffer if no allocated yet, or the
+		 * current buffer has incorrect size */
+		free(cxt->firstsector);
+
+		DBG(CXT, ul_debugobj(cxt, "initialize in-memory first sector "
+				"buffer [sector_size=%lu]", cxt->sector_size));
+		cxt->firstsector = calloc(1, cxt->sector_size);
+		if (!cxt->firstsector)
+			return -ENOMEM;
+
+		cxt->firstsector_bufsz = cxt->sector_size;
+		return 0;
+	}
 
 	DBG(CXT, ul_debugobj(cxt, "zeroize in-memory first sector buffer"));
-	memset(cxt->firstsector, 0, cxt->sector_size);
+	memset(cxt->firstsector, 0, cxt->firstsector_bufsz);
+	return 0;
 }
 
 int fdisk_read_firstsector(struct fdisk_context *cxt)
 {
 	ssize_t r;
+	int rc;
 
 	assert(cxt);
 	assert(cxt->sector_size);
 
-	DBG(CXT, ul_debugobj(cxt, "initialize first sector "
-				"buffer [sector_size=%lu]", cxt->sector_size));
+	rc = fdisk_init_firstsector_buffer(cxt);
+	if (rc)
+		return rc;
 
-	if (!cxt->firstsector) {
-		cxt->firstsector = calloc(1, cxt->sector_size);
-		if (!cxt->firstsector)
-			return -ENOMEM;
-	} else
-		fdisk_zeroize_firstsector(cxt);
+	assert(cxt->sector_size == cxt->firstsector_bufsz);
+
+	DBG(CXT, ul_debugobj(cxt, "reading first sector "
+				"buffer [sector_size=%lu]", cxt->sector_size));
 
 	r = read(cxt->dev_fd, cxt->firstsector, cxt->sector_size);