* [PATCH v2 1/1] dax: Fix stack overflow when mounting fsdax pmem device
@ 2020-09-16 13:39 Adrian Huang
2020-09-16 15:00 ` Jan Kara
2020-09-17 9:50 ` Dan Williams
0 siblings, 2 replies; 3+ messages in thread
From: Adrian Huang @ 2020-09-16 13:39 UTC (permalink / raw)
To: linux-nvdimm
Cc: Adrian Huang, Coly Li, Jan Kara, Mikulas Patocka,
Alasdair Kergon, Mike Snitzer, Adrian Huang
From: Adrian Huang <ahuang12@lenovo.com>
When mounting fsdax pmem device, commit 6180bb446ab6 ("dax: fix
detection of dax support for non-persistent memory block devices")
introduces the stack overflow [1][2]. Here is the call path for
mounting ext4 file system:
ext4_fill_super
bdev_dax_supported
__bdev_dax_supported
dax_supported
generic_fsdax_supported
__generic_fsdax_supported
bdev_dax_supported
The call path leads to the infinite calling loop, so we cannot
call bdev_dax_supported() in __generic_fsdax_supported(). The sanity
checking of the variable 'dax_dev' is moved prior to the two
bdev_dax_pgoff() checks [3][4].
[1] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/BULZHRILK7N2WS2JVISNF2QZNRQK6JU4/
[2] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/OOZGFY3RNQGTGJJCH52YXCSYIDXMOPXO/
[3] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SMQW2LY3QHPXOAW76RKNSCGG3QJFO7HT/
[4] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/7E2X6UGX5RQ2ISGYNAF66VLY5BKBFI4M/
Fixes: 6180bb446ab6 ("dax: fix detection of dax support for non-persistent memory block devices")
Cc: Coly Li <colyli@suse.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Pittman <jpittman@redhat.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
---
v1->v2
* Remove the checking for the returned value '-EOPNOTSUPP' of
dax_direct_access(). Jan has prepared a patch to address the
issue in dm.
---
drivers/dax/super.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e5767c83ea23..11d0541e6f8f 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -85,6 +85,12 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
return false;
}
+ if (!dax_dev) {
+ pr_debug("%s: error: dax unsupported by block device\n",
+ bdevname(bdev, buf));
+ return false;
+ }
+
err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
if (err) {
pr_info("%s: error: unaligned partition for dax\n",
@@ -100,12 +106,6 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
return false;
}
- if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
- pr_debug("%s: error: dax unsupported by block device\n",
- bdevname(bdev, buf));
- return false;
- }
-
id = dax_read_lock();
len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
--
2.17.1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2 1/1] dax: Fix stack overflow when mounting fsdax pmem device
2020-09-16 13:39 [PATCH v2 1/1] dax: Fix stack overflow when mounting fsdax pmem device Adrian Huang
@ 2020-09-16 15:00 ` Jan Kara
2020-09-17 9:50 ` Dan Williams
1 sibling, 0 replies; 3+ messages in thread
From: Jan Kara @ 2020-09-16 15:00 UTC (permalink / raw)
To: Adrian Huang
Cc: linux-nvdimm, Coly Li, Jan Kara, Mikulas Patocka,
Alasdair Kergon, Mike Snitzer, Adrian Huang
On Wed 16-09-20 21:39:23, Adrian Huang wrote:
> From: Adrian Huang <ahuang12@lenovo.com>
>
> When mounting fsdax pmem device, commit 6180bb446ab6 ("dax: fix
> detection of dax support for non-persistent memory block devices")
> introduces the stack overflow [1][2]. Here is the call path for
> mounting ext4 file system:
> ext4_fill_super
> bdev_dax_supported
> __bdev_dax_supported
> dax_supported
> generic_fsdax_supported
> __generic_fsdax_supported
> bdev_dax_supported
>
> The call path leads to the infinite calling loop, so we cannot
> call bdev_dax_supported() in __generic_fsdax_supported(). The sanity
> checking of the variable 'dax_dev' is moved prior to the two
> bdev_dax_pgoff() checks [3][4].
>
> [1] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/BULZHRILK7N2WS2JVISNF2QZNRQK6JU4/
> [2] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/OOZGFY3RNQGTGJJCH52YXCSYIDXMOPXO/
> [3] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SMQW2LY3QHPXOAW76RKNSCGG3QJFO7HT/
> [4] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/7E2X6UGX5RQ2ISGYNAF66VLY5BKBFI4M/
>
> Fixes: 6180bb446ab6 ("dax: fix detection of dax support for non-persistent memory block devices")
> Cc: Coly Li <colyli@suse.de>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: John Pittman <jpittman@redhat.com>
> Cc: Mikulas Patocka <mpatocka@redhat.com>
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
The patch looks good to me. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Honza
> ---
> v1->v2
> * Remove the checking for the returned value '-EOPNOTSUPP' of
> dax_direct_access(). Jan has prepared a patch to address the
> issue in dm.
> ---
> drivers/dax/super.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index e5767c83ea23..11d0541e6f8f 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -85,6 +85,12 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
> return false;
> }
>
> + if (!dax_dev) {
> + pr_debug("%s: error: dax unsupported by block device\n",
> + bdevname(bdev, buf));
> + return false;
> + }
> +
> err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
> if (err) {
> pr_info("%s: error: unaligned partition for dax\n",
> @@ -100,12 +106,6 @@ bool __generic_fsdax_supported(struct dax_device *dax_dev,
> return false;
> }
>
> - if (!dax_dev || !bdev_dax_supported(bdev, blocksize)) {
> - pr_debug("%s: error: dax unsupported by block device\n",
> - bdevname(bdev, buf));
> - return false;
> - }
> -
> id = dax_read_lock();
> len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
> len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
> --
> 2.17.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 1/1] dax: Fix stack overflow when mounting fsdax pmem device
2020-09-16 13:39 [PATCH v2 1/1] dax: Fix stack overflow when mounting fsdax pmem device Adrian Huang
2020-09-16 15:00 ` Jan Kara
@ 2020-09-17 9:50 ` Dan Williams
1 sibling, 0 replies; 3+ messages in thread
From: Dan Williams @ 2020-09-17 9:50 UTC (permalink / raw)
To: Adrian Huang
Cc: linux-nvdimm, Coly Li, Jan Kara, Mikulas Patocka,
Alasdair Kergon, Mike Snitzer, Adrian Huang
On Wed, Sep 16, 2020 at 6:41 AM Adrian Huang <adrianhuang0701@gmail.com> wrote:
>
> From: Adrian Huang <ahuang12@lenovo.com>
>
> When mounting fsdax pmem device, commit 6180bb446ab6 ("dax: fix
> detection of dax support for non-persistent memory block devices")
> introduces the stack overflow [1][2]. Here is the call path for
> mounting ext4 file system:
> ext4_fill_super
> bdev_dax_supported
> __bdev_dax_supported
> dax_supported
> generic_fsdax_supported
> __generic_fsdax_supported
> bdev_dax_supported
>
> The call path leads to the infinite calling loop, so we cannot
> call bdev_dax_supported() in __generic_fsdax_supported(). The sanity
> checking of the variable 'dax_dev' is moved prior to the two
> bdev_dax_pgoff() checks [3][4].
Looks good, and passes tests.
> [1] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/BULZHRILK7N2WS2JVISNF2QZNRQK6JU4/
> [2] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/thread/OOZGFY3RNQGTGJJCH52YXCSYIDXMOPXO/
> [3] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/SMQW2LY3QHPXOAW76RKNSCGG3QJFO7HT/
> [4] https://lists.01.org/hyperkitty/list/linux-nvdimm@lists.01.org/message/7E2X6UGX5RQ2ISGYNAF66VLY5BKBFI4M/
lists.01.org has already proven to not be reliable for maintaining
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2020-09-16 15:00 ` Jan Kara
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