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dax: Check the end of the block-device capacity with dax_direct_access()
The checks in __bdev_dax_supported() helped mitigate a potential data corruption bug in the pmem driver's handling of section alignment padding. Strengthen the checks, including checking the end of the range, to validate the dev_pagemap, Xarray entries, and sector-to-pfn translation established for pmem namespaces. Acked-by: Jan Kara <jack@suse.cz> Cc: "Darrick J. Wong" <darrick.wong@oracle.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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@ -86,12 +86,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
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{
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struct dax_device *dax_dev;
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bool dax_enabled = false;
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pgoff_t pgoff, pgoff_end;
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struct request_queue *q;
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pgoff_t pgoff;
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int err, id;
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pfn_t pfn;
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long len;
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char buf[BDEVNAME_SIZE];
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void *kaddr, *end_kaddr;
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pfn_t pfn, end_pfn;
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sector_t last_page;
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long len, len2;
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int err, id;
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if (blocksize != PAGE_SIZE) {
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pr_debug("%s: error: unsupported blocksize for dax\n",
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@ -113,6 +115,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
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return false;
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}
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last_page = PFN_DOWN(i_size_read(bdev->bd_inode) - 1) * 8;
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err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
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if (err) {
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pr_debug("%s: error: unaligned partition for dax\n",
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bdevname(bdev, buf));
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return false;
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}
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dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
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if (!dax_dev) {
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pr_debug("%s: error: device does not support dax\n",
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@ -121,14 +131,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
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}
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id = dax_read_lock();
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len = dax_direct_access(dax_dev, pgoff, 1, NULL, &pfn);
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len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
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len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
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dax_read_unlock(id);
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put_dax(dax_dev);
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if (len < 1) {
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if (len < 1 || len2 < 1) {
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pr_debug("%s: error: dax access failed (%ld)\n",
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bdevname(bdev, buf), len);
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bdevname(bdev, buf), len < 1 ? len : len2);
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return false;
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}
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@ -143,13 +154,20 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
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*/
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WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
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dax_enabled = true;
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} else if (pfn_t_devmap(pfn)) {
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struct dev_pagemap *pgmap;
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} else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) {
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struct dev_pagemap *pgmap, *end_pgmap;
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pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
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if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
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end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL);
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if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX
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&& pfn_t_to_page(pfn)->pgmap == pgmap
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&& pfn_t_to_page(end_pfn)->pgmap == pgmap
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&& pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr))
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&& pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr)))
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dax_enabled = true;
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put_dev_pagemap(pgmap);
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put_dev_pagemap(end_pgmap);
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}
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if (!dax_enabled) {
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