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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>
This commit is contained in:
Dan Williams 2019-02-20 21:12:50 -08:00
parent fa7d2e639c
commit ad428cdb52
1 changed files with 28 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
drivers/dax/super.c
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@ -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) {