[libata] More robust parsing for IDENTIFY DEVICE multi_count field (e18086d6) · Commits · 戴 / test

Make libata more robust when parsing the multi_count field from a drive's identify data. This prevents us from attempting to use dubious multi_count values ad infinitum. Reset dev->multi_count to zero and reprobe it each time through this routine, as it can change on device reset. Also ensure that the reported "maximum" value is valid and is a power of two, and that the reported "count" value is valid and also a power of two. And that the "count" value is not greater than the "maximum" value. Signed-off-by:

Mark Lord <mlord@pobox.com> Signed-off-by:

Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-core.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -57,6 +57,7 @@
		#include <linux/scatterlist.h>
		#include <linux/io.h>
		#include <linux/async.h>
		#include <linux/log2.h>
		#include <scsi/scsi.h>
		#include <scsi/scsi_cmnd.h>
		#include <scsi/scsi_host.h>
		@@ -2389,6 +2390,7 @@ int ata_dev_configure(struct ata_device *dev)
		dev->cylinders = 0;
		dev->heads = 0;
		dev->sectors = 0;
		dev->multi_count = 0;

		/*
		* common ATA, ATAPI feature tests
		@@ -2426,8 +2428,15 @@ int ata_dev_configure(struct ata_device *dev)

		dev->n_sectors = ata_id_n_sectors(id);

		if (dev->id[59] & 0x100)
		dev->multi_count = dev->id[59] & 0xff;
		/* get current R/W Multiple count setting */
		if ((dev->id[47] >> 8) == 0x80 && (dev->id[59] & 0x100)) {
		unsigned int max = dev->id[47] & 0xff;
		unsigned int cnt = dev->id[59] & 0xff;
		/* only recognize/allow powers of two here */
		if (is_power_of_2(max) && is_power_of_2(cnt))
		if (cnt <= max)
		dev->multi_count = cnt;
		}

		if (ata_id_has_lba(id)) {
		const char *lba_desc;

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