From ad428cdb525a97d15c0349fdc80f3d58befb50df Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Wed, 20 Feb 2019 21:12:50 -0800 Subject: 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 Cc: "Darrick J. Wong" Signed-off-by: Dan Williams --- drivers/dax/super.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 6e928f37d084..0cb8c30ea278 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -86,12 +86,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) { struct dax_device *dax_dev; bool dax_enabled = false; + pgoff_t pgoff, pgoff_end; struct request_queue *q; - pgoff_t pgoff; - int err, id; - pfn_t pfn; - long len; char buf[BDEVNAME_SIZE]; + void *kaddr, *end_kaddr; + pfn_t pfn, end_pfn; + sector_t last_page; + long len, len2; + int err, id; if (blocksize != PAGE_SIZE) { pr_debug("%s: error: unsupported blocksize for dax\n", @@ -113,6 +115,14 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) return false; } + last_page = PFN_DOWN(i_size_read(bdev->bd_inode) - 1) * 8; + err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end); + if (err) { + pr_debug("%s: error: unaligned partition for dax\n", + bdevname(bdev, buf)); + return false; + } + dax_dev = dax_get_by_host(bdev->bd_disk->disk_name); if (!dax_dev) { pr_debug("%s: error: device does not support dax\n", @@ -121,14 +131,15 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) } id = dax_read_lock(); - len = dax_direct_access(dax_dev, pgoff, 1, NULL, &pfn); + len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn); + len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn); dax_read_unlock(id); put_dax(dax_dev); - if (len < 1) { + if (len < 1 || len2 < 1) { pr_debug("%s: error: dax access failed (%ld)\n", - bdevname(bdev, buf), len); + bdevname(bdev, buf), len < 1 ? len : len2); return false; } @@ -143,13 +154,20 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize) */ WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API)); dax_enabled = true; - } else if (pfn_t_devmap(pfn)) { - struct dev_pagemap *pgmap; + } else if (pfn_t_devmap(pfn) && pfn_t_devmap(end_pfn)) { + struct dev_pagemap *pgmap, *end_pgmap; pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL); - if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX) + end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL); + if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX + && pfn_t_to_page(pfn)->pgmap == pgmap + && pfn_t_to_page(end_pfn)->pgmap == pgmap + && pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr)) + && pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr))) dax_enabled = true; put_dev_pagemap(pgmap); + put_dev_pagemap(end_pgmap); + } if (!dax_enabled) { -- cgit