ide: memory overrun in ide_get_identity_ioctl() on big endian machine…

…s using ioctl HDIO_OBSOLETE_IDENTITY

This patch fixes a memory overrun in function ide_get_identity_ioctl() which
chooses the size of a memory buffer depending on the ioctl command that led
to the function call, however, passes that buffer to a function which needs the
buffer size to be always chosen unconditionally.

Due to conditional compilation the memory overrun can only happen on big endian
machines. The error can be triggered using ioctl HDIO_OBSOLETE_IDENTITY. Usage
of ioctl HDIO_GET_IDENTITY is safe.

Signed-off-by: Christian Engelmayer <christian.engelmayer@frequentis.com>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/ide/ide-ioctls.c

@@ -64,7 +64,8 @@ static int ide_get_identity_ioctl(ide_drive_t *drive, unsigned int cmd,
 		goto out;
 	}
 
-	id = kmalloc(size, GFP_KERNEL);
+	/* ata_id_to_hd_driveid() relies on 'id' to be fully allocated. */
+	id = kmalloc(ATA_ID_WORDS * 2, GFP_KERNEL);
 	if (id == NULL) {
 		rc = -ENOMEM;
 		goto out;