[PATCH v3 06/14] ide: Refuse an ATAPI block size atapi_read() cannot read

[Ana Bobillo <anabobillo3@gmail.com>]

From: Ana Bobillo <anabobillo3@gmail.com>

atapi_inquiry() takes the block size from the READ CAPACITY reply of an
ATAPI device as it is, while atapi_read() asks the device for, and moves
the buffer on by, ATAPI_READ_BLOCK_SIZE (2048) bytes for every block.
With any other block size the callers' buffers, which are sized by
blksz, do not match what atapi_read() writes into them: a 512-byte block
size makes a read of several blocks write past the end of the buffer.

Some CD drives report another block size although they read 2048-byte
blocks: 2340 (HP 4020i CD-Recorder), 2352 (Philips CD-Writers) or 0.
Take these as ATAPI_READ_BLOCK_SIZE, as Linux does in get_sectorsize(),
so that a drive reporting 0, which ide_probe() skipped until now, is
read with 2048-byte blocks too. Refuse any other value: a device
reporting one is left with a zero block size, which ide_probe() skips,
as for a drive without a medium. This refuses drives with 512-byte
blocks, such as ZIP drives, whose reads of more than one block already
overran the buffer; supporting them needs atapi_read() to use the block
size of the device.

Signed-off-by: Ana Bobillo <anabobillo3@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
---
(no changes since v2)

Changes in v2:
- Take 0, 2340 and 2352 as 2048, as Linux get_sectorsize() does (Simon)
- Say what is skipped in the message (Simon)

 drivers/block/ide.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/block/ide.c b/drivers/block/ide.c
index 44ce054bdf5..56e55bc8bc1 100644
--- a/drivers/block/ide.c
+++ b/drivers/block/ide.c
@@ -450,6 +450,7 @@ static void atapi_inquiry(struct blk_desc *desc)
 {
 	u8 ccb[12];	/* Command descriptor block */
 	u8 iobuf[64];	/* temp buf */
+	ulong blksz;
 	u8 c;
 	int device;
 
@@ -514,10 +515,28 @@ static void atapi_inquiry(struct blk_desc *desc)
 		  iobuf[0], iobuf[1], iobuf[2], iobuf[3],
 		  iobuf[4], iobuf[5], iobuf[6], iobuf[7]);
 
+	blksz = (ulong)iobuf[4] << 24 | (ulong)iobuf[5] << 16 |
+		(ulong)iobuf[6] << 8 | (ulong)iobuf[7];
+	/*
+	 * atapi_read() transfers ATAPI_READ_BLOCK_SIZE bytes per block. Some
+	 * CD drives report another size although they read 2048-byte blocks,
+	 * which Linux takes as 2048 in get_sectorsize(): do the same.
+	 */
+	switch (blksz) {
+	case 0:
+	case 2340:	/* HP 4020i CD-Recorder */
+	case 2352:	/* Philips CD-Writers */
+		blksz = ATAPI_READ_BLOCK_SIZE;
+		break;
+	case ATAPI_READ_BLOCK_SIZE:
+		break;
+	default:
+		printf("ATAPI block size %lu not supported, skipping\n", blksz);
+		return;
+	}
 	desc->lba = (ulong)iobuf[0] << 24 | (ulong)iobuf[1] << 16 |
 		(ulong)iobuf[2] << 8 | (ulong)iobuf[3];
-	desc->blksz = (ulong)iobuf[4] << 24 | (ulong)iobuf[5] << 16 |
-		(ulong)iobuf[6] << 8 | (ulong)iobuf[7];
+	desc->blksz = blksz;
 	desc->log2blksz = LOG2(desc->blksz);
 
 	/* ATAPI devices cannot use 48bit addressing (ATA/ATAPI v7) */