* [PATCH v2] async_pq: Remove VLA usage
@ 2018-05-05 7:58 Kyle Spiers
2018-05-10 20:57 ` Kees Cook
2018-05-29 22:37 ` Dan Williams
0 siblings, 2 replies; 7+ messages in thread
From: Kyle Spiers @ 2018-05-05 7:58 UTC (permalink / raw)
To: dan.j.williams
Cc: davem, keescook, vinod.koul, ray.jui, linux-crypto, linux-kernel,
Kyle Spiers
In the quest to remove VLAs from the kernel[1], this moves the
allocation of coefs and blocks from the stack to being kmalloc()ed.
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Kyle Spiers <ksspiers@google.com>
---
Forgot to add slab.h
---
crypto/async_tx/async_pq.c | 18 ++++++++++++++----
crypto/async_tx/raid6test.c | 9 ++++++++-
2 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
index 56bd612927ab..af1912313a23 100644
--- a/crypto/async_tx/async_pq.c
+++ b/crypto/async_tx/async_pq.c
@@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
(src_cnt <= dma_maxpq(device, 0) ||
dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
is_dma_pq_aligned(device, offset, 0, len)) {
- struct dma_async_tx_descriptor *tx;
+ struct dma_async_tx_descriptor *tx = NULL;
enum dma_ctrl_flags dma_flags = 0;
- unsigned char coefs[src_cnt];
+ unsigned char *coefs;
int i, j;
/* run the p+q asynchronously */
@@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
* sources and update the coefficients accordingly
*/
unmap->len = len;
+ coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL);
+ if (!coefs)
+ goto out;
for (i = 0, j = 0; i < src_cnt; i++) {
if (blocks[i] == NULL)
continue;
@@ -240,7 +243,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
}
tx = do_async_gen_syndrome(chan, coefs, j, unmap, dma_flags, submit);
+out:
dmaengine_unmap_put(unmap);
+ kfree(coefs);
return tx;
}
@@ -298,8 +303,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
{
struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
struct dma_device *device = chan ? chan->device : NULL;
- struct dma_async_tx_descriptor *tx;
- unsigned char coefs[disks-2];
+ struct dma_async_tx_descriptor *tx = NULL;
+ unsigned char *coefs = NULL;
enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
struct dmaengine_unmap_data *unmap = NULL;
@@ -318,6 +323,9 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
__func__, disks, len);
unmap->len = len;
+ coefs = kmalloc_array(disks - 2, sizeof(*coefs), GFP_KERNEL);
+ if (!coefs)
+ goto out;
for (i = 0; i < disks-2; i++)
if (likely(blocks[i])) {
unmap->addr[j] = dma_map_page(dev, blocks[i],
@@ -423,6 +431,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
async_tx_sync_epilog(submit);
tx = NULL;
}
+out:
+ kfree(coefs);
dmaengine_unmap_put(unmap);
return tx;
diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c
index dad95f45b88f..4237a5ae8f42 100644
--- a/crypto/async_tx/raid6test.c
+++ b/crypto/async_tx/raid6test.c
@@ -24,6 +24,7 @@
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/module.h>
+#include <linux/slab.h>
#undef pr
#define pr(fmt, args...) pr_info("raid6test: " fmt, ##args)
@@ -81,11 +82,16 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
} else {
- struct page *blocks[disks];
+ struct page **blocks;
struct page *dest;
int count = 0;
int i;
+ blocks = kmalloc_array(disks, sizeof(*blocks),
+ GFP_KERNEL);
+ if (!blocks)
+ return;
+
/* data+Q failure. Reconstruct data from P,
* then rebuild syndrome
*/
@@ -101,6 +107,7 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
init_async_submit(&submit, 0, tx, NULL, NULL, addr_conv);
tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
+ kfree(blocks);
}
} else {
if (failb == disks-2) {
--
2.17.0.441.gb46fe60e1d-goog
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-05 7:58 [PATCH v2] async_pq: Remove VLA usage Kyle Spiers
@ 2018-05-10 20:57 ` Kees Cook
2018-05-29 22:24 ` Kees Cook
2018-05-29 22:37 ` Dan Williams
1 sibling, 1 reply; 7+ messages in thread
From: Kees Cook @ 2018-05-10 20:57 UTC (permalink / raw)
To: Kyle Spiers, Dan Williams, vinod.koul, Herbert Xu
Cc: David S. Miller, ray.jui, linux-crypto, LKML
On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
> In the quest to remove VLAs from the kernel[1], this moves the
> allocation of coefs and blocks from the stack to being kmalloc()ed.
>
> [1] https://lkml.org/lkml/2018/3/7/621
>
> Signed-off-by: Kyle Spiers <ksspiers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Is this something that should go via Vinod, Dan, or direct through
Herbert's crypto tree?
Thanks!
-Kees
> ---
> Forgot to add slab.h
> ---
> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
> crypto/async_tx/raid6test.c | 9 ++++++++-
> 2 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
> index 56bd612927ab..af1912313a23 100644
> --- a/crypto/async_tx/async_pq.c
> +++ b/crypto/async_tx/async_pq.c
> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
> (src_cnt <= dma_maxpq(device, 0) ||
> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
> is_dma_pq_aligned(device, offset, 0, len)) {
> - struct dma_async_tx_descriptor *tx;
> + struct dma_async_tx_descriptor *tx = NULL;
> enum dma_ctrl_flags dma_flags = 0;
> - unsigned char coefs[src_cnt];
> + unsigned char *coefs;
> int i, j;
>
> /* run the p+q asynchronously */
> @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
> * sources and update the coefficients accordingly
> */
> unmap->len = len;
> + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL);
> + if (!coefs)
> + goto out;
> for (i = 0, j = 0; i < src_cnt; i++) {
> if (blocks[i] == NULL)
> continue;
> @@ -240,7 +243,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
> }
>
> tx = do_async_gen_syndrome(chan, coefs, j, unmap, dma_flags, submit);
> +out:
> dmaengine_unmap_put(unmap);
> + kfree(coefs);
> return tx;
> }
>
> @@ -298,8 +303,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
> {
> struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
> struct dma_device *device = chan ? chan->device : NULL;
> - struct dma_async_tx_descriptor *tx;
> - unsigned char coefs[disks-2];
> + struct dma_async_tx_descriptor *tx = NULL;
> + unsigned char *coefs = NULL;
> enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
> struct dmaengine_unmap_data *unmap = NULL;
>
> @@ -318,6 +323,9 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
> __func__, disks, len);
>
> unmap->len = len;
> + coefs = kmalloc_array(disks - 2, sizeof(*coefs), GFP_KERNEL);
> + if (!coefs)
> + goto out;
> for (i = 0; i < disks-2; i++)
> if (likely(blocks[i])) {
> unmap->addr[j] = dma_map_page(dev, blocks[i],
> @@ -423,6 +431,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
> async_tx_sync_epilog(submit);
> tx = NULL;
> }
> +out:
> + kfree(coefs);
> dmaengine_unmap_put(unmap);
>
> return tx;
> diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c
> index dad95f45b88f..4237a5ae8f42 100644
> --- a/crypto/async_tx/raid6test.c
> +++ b/crypto/async_tx/raid6test.c
> @@ -24,6 +24,7 @@
> #include <linux/mm.h>
> #include <linux/random.h>
> #include <linux/module.h>
> +#include <linux/slab.h>
>
> #undef pr
> #define pr(fmt, args...) pr_info("raid6test: " fmt, ##args)
> @@ -81,11 +82,16 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
> init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
> tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
> } else {
> - struct page *blocks[disks];
> + struct page **blocks;
> struct page *dest;
> int count = 0;
> int i;
>
> + blocks = kmalloc_array(disks, sizeof(*blocks),
> + GFP_KERNEL);
> + if (!blocks)
> + return;
> +
> /* data+Q failure. Reconstruct data from P,
> * then rebuild syndrome
> */
> @@ -101,6 +107,7 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
>
> init_async_submit(&submit, 0, tx, NULL, NULL, addr_conv);
> tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
> + kfree(blocks);
> }
> } else {
> if (failb == disks-2) {
> --
> 2.17.0.441.gb46fe60e1d-goog
>
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-10 20:57 ` Kees Cook
@ 2018-05-29 22:24 ` Kees Cook
0 siblings, 0 replies; 7+ messages in thread
From: Kees Cook @ 2018-05-29 22:24 UTC (permalink / raw)
To: Kyle Spiers, Dan Williams, vinod.koul, Herbert Xu
Cc: David S. Miller, ray.jui, linux-crypto, LKML
On Thu, May 10, 2018 at 1:57 PM, Kees Cook <keescook@chromium.org> wrote:
> On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
>> In the quest to remove VLAs from the kernel[1], this moves the
>> allocation of coefs and blocks from the stack to being kmalloc()ed.
>>
>> [1] https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Kyle Spiers <ksspiers@google.com>
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> Is this something that should go via Vinod, Dan, or direct through
> Herbert's crypto tree?
Friendly ping. Any news on this patch?
Thanks!
-Kees
>
> Thanks!
>
> -Kees
>
>> ---
>> Forgot to add slab.h
>> ---
>> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
>> crypto/async_tx/raid6test.c | 9 ++++++++-
>> 2 files changed, 22 insertions(+), 5 deletions(-)
>>
>> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
>> index 56bd612927ab..af1912313a23 100644
>> --- a/crypto/async_tx/async_pq.c
>> +++ b/crypto/async_tx/async_pq.c
>> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>> (src_cnt <= dma_maxpq(device, 0) ||
>> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
>> is_dma_pq_aligned(device, offset, 0, len)) {
>> - struct dma_async_tx_descriptor *tx;
>> + struct dma_async_tx_descriptor *tx = NULL;
>> enum dma_ctrl_flags dma_flags = 0;
>> - unsigned char coefs[src_cnt];
>> + unsigned char *coefs;
>> int i, j;
>>
>> /* run the p+q asynchronously */
>> @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>> * sources and update the coefficients accordingly
>> */
>> unmap->len = len;
>> + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL);
>> + if (!coefs)
>> + goto out;
>> for (i = 0, j = 0; i < src_cnt; i++) {
>> if (blocks[i] == NULL)
>> continue;
>> @@ -240,7 +243,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>> }
>>
>> tx = do_async_gen_syndrome(chan, coefs, j, unmap, dma_flags, submit);
>> +out:
>> dmaengine_unmap_put(unmap);
>> + kfree(coefs);
>> return tx;
>> }
>>
>> @@ -298,8 +303,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
>> {
>> struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len);
>> struct dma_device *device = chan ? chan->device : NULL;
>> - struct dma_async_tx_descriptor *tx;
>> - unsigned char coefs[disks-2];
>> + struct dma_async_tx_descriptor *tx = NULL;
>> + unsigned char *coefs = NULL;
>> enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0;
>> struct dmaengine_unmap_data *unmap = NULL;
>>
>> @@ -318,6 +323,9 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
>> __func__, disks, len);
>>
>> unmap->len = len;
>> + coefs = kmalloc_array(disks - 2, sizeof(*coefs), GFP_KERNEL);
>> + if (!coefs)
>> + goto out;
>> for (i = 0; i < disks-2; i++)
>> if (likely(blocks[i])) {
>> unmap->addr[j] = dma_map_page(dev, blocks[i],
>> @@ -423,6 +431,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks,
>> async_tx_sync_epilog(submit);
>> tx = NULL;
>> }
>> +out:
>> + kfree(coefs);
>> dmaengine_unmap_put(unmap);
>>
>> return tx;
>> diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c
>> index dad95f45b88f..4237a5ae8f42 100644
>> --- a/crypto/async_tx/raid6test.c
>> +++ b/crypto/async_tx/raid6test.c
>> @@ -24,6 +24,7 @@
>> #include <linux/mm.h>
>> #include <linux/random.h>
>> #include <linux/module.h>
>> +#include <linux/slab.h>
>>
>> #undef pr
>> #define pr(fmt, args...) pr_info("raid6test: " fmt, ##args)
>> @@ -81,11 +82,16 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
>> init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv);
>> tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
>> } else {
>> - struct page *blocks[disks];
>> + struct page **blocks;
>> struct page *dest;
>> int count = 0;
>> int i;
>>
>> + blocks = kmalloc_array(disks, sizeof(*blocks),
>> + GFP_KERNEL);
>> + if (!blocks)
>> + return;
>> +
>> /* data+Q failure. Reconstruct data from P,
>> * then rebuild syndrome
>> */
>> @@ -101,6 +107,7 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru
>>
>> init_async_submit(&submit, 0, tx, NULL, NULL, addr_conv);
>> tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit);
>> + kfree(blocks);
>> }
>> } else {
>> if (failb == disks-2) {
>> --
>> 2.17.0.441.gb46fe60e1d-goog
>>
>
>
>
> --
> Kees Cook
> Pixel Security
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-05 7:58 [PATCH v2] async_pq: Remove VLA usage Kyle Spiers
2018-05-10 20:57 ` Kees Cook
@ 2018-05-29 22:37 ` Dan Williams
2018-05-29 22:40 ` Dan Williams
1 sibling, 1 reply; 7+ messages in thread
From: Dan Williams @ 2018-05-29 22:37 UTC (permalink / raw)
To: Kyle Spiers
Cc: David Miller, Kees Cook, Vinod Koul, ray.jui, linux-crypto,
Linux Kernel Mailing List, linux-raid
[ adding linux-raid ]
Apologies for the delay, the recent ping from Kees made me take a closer look.
On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
> In the quest to remove VLAs from the kernel[1], this moves the
> allocation of coefs and blocks from the stack to being kmalloc()ed.
>
> [1] https://lkml.org/lkml/2018/3/7/621
>
> Signed-off-by: Kyle Spiers <ksspiers@google.com>
> ---
> Forgot to add slab.h
> ---
> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
> crypto/async_tx/raid6test.c | 9 ++++++++-
> 2 files changed, 22 insertions(+), 5 deletions(-)
>
> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
> index 56bd612927ab..af1912313a23 100644
> --- a/crypto/async_tx/async_pq.c
> +++ b/crypto/async_tx/async_pq.c
> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
> (src_cnt <= dma_maxpq(device, 0) ||
> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
> is_dma_pq_aligned(device, offset, 0, len)) {
> - struct dma_async_tx_descriptor *tx;
> + struct dma_async_tx_descriptor *tx = NULL;
> enum dma_ctrl_flags dma_flags = 0;
> - unsigned char coefs[src_cnt];
> + unsigned char *coefs;
> int i, j;
>
> /* run the p+q asynchronously */
> @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
> * sources and update the coefficients accordingly
> */
> unmap->len = len;
> + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL);
At a minimum this needs to be GFP_NOIO since raid may be in the
page-reclaim path.
However, I think it may be better to allocate this with the rest of
the stripe resources and pass it in as a scratch buffer. See the usage
/ implementation of scribble_alloc() in drivers/md/raid5.c.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-29 22:37 ` Dan Williams
@ 2018-05-29 22:40 ` Dan Williams
2018-05-30 21:33 ` Kees Cook
0 siblings, 1 reply; 7+ messages in thread
From: Dan Williams @ 2018-05-29 22:40 UTC (permalink / raw)
To: Kyle Spiers
Cc: David Miller, Kees Cook, ray.jui, linux-crypto,
Linux Kernel Mailing List, linux-raid, vkoul
[ add Vinod's korg address ]
On Tue, May 29, 2018 at 3:37 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> [ adding linux-raid ]
>
> Apologies for the delay, the recent ping from Kees made me take a closer look.
>
> On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
>> In the quest to remove VLAs from the kernel[1], this moves the
>> allocation of coefs and blocks from the stack to being kmalloc()ed.
>>
>> [1] https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Kyle Spiers <ksspiers@google.com>
>> ---
>> Forgot to add slab.h
>> ---
>> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
>> crypto/async_tx/raid6test.c | 9 ++++++++-
>> 2 files changed, 22 insertions(+), 5 deletions(-)
>>
>> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
>> index 56bd612927ab..af1912313a23 100644
>> --- a/crypto/async_tx/async_pq.c
>> +++ b/crypto/async_tx/async_pq.c
>> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>> (src_cnt <= dma_maxpq(device, 0) ||
>> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
>> is_dma_pq_aligned(device, offset, 0, len)) {
>> - struct dma_async_tx_descriptor *tx;
>> + struct dma_async_tx_descriptor *tx = NULL;
>> enum dma_ctrl_flags dma_flags = 0;
>> - unsigned char coefs[src_cnt];
>> + unsigned char *coefs;
>> int i, j;
>>
>> /* run the p+q asynchronously */
>> @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>> * sources and update the coefficients accordingly
>> */
>> unmap->len = len;
>> + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL);
>
> At a minimum this needs to be GFP_NOIO since raid may be in the
> page-reclaim path.
>
> However, I think it may be better to allocate this with the rest of
> the stripe resources and pass it in as a scratch buffer. See the usage
> / implementation of scribble_alloc() in drivers/md/raid5.c.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-29 22:40 ` Dan Williams
@ 2018-05-30 21:33 ` Kees Cook
2018-05-30 22:04 ` Dan Williams
0 siblings, 1 reply; 7+ messages in thread
From: Kees Cook @ 2018-05-30 21:33 UTC (permalink / raw)
To: Dan Williams
Cc: Kyle Spiers, David Miller, ray.jui, linux-crypto,
Linux Kernel Mailing List, linux-raid, vkoul
On Tue, May 29, 2018 at 3:40 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> [ add Vinod's korg address ]
>
> On Tue, May 29, 2018 at 3:37 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>> [ adding linux-raid ]
>>
>> Apologies for the delay, the recent ping from Kees made me take a closer look.
>>
>> On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
>>> In the quest to remove VLAs from the kernel[1], this moves the
>>> allocation of coefs and blocks from the stack to being kmalloc()ed.
>>>
>>> [1] https://lkml.org/lkml/2018/3/7/621
>>>
>>> Signed-off-by: Kyle Spiers <ksspiers@google.com>
>>> ---
>>> Forgot to add slab.h
>>> ---
>>> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
>>> crypto/async_tx/raid6test.c | 9 ++++++++-
>>> 2 files changed, 22 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
>>> index 56bd612927ab..af1912313a23 100644
>>> --- a/crypto/async_tx/async_pq.c
>>> +++ b/crypto/async_tx/async_pq.c
>>> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>>> (src_cnt <= dma_maxpq(device, 0) ||
>>> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
>>> is_dma_pq_aligned(device, offset, 0, len)) {
>>> - struct dma_async_tx_descriptor *tx;
>>> + struct dma_async_tx_descriptor *tx = NULL;
>>> enum dma_ctrl_flags dma_flags = 0;
>>> - unsigned char coefs[src_cnt];
>>> + unsigned char *coefs;
>> At a minimum this needs to be GFP_NOIO since raid may be in the
>> page-reclaim path.
>>
>> However, I think it may be better to allocate this with the rest of
>> the stripe resources and pass it in as a scratch buffer. See the usage
>> / implementation of scribble_alloc() in drivers/md/raid5.c.
Given this:
int src_cnt = disks - 2;
...
BUG_ON(disks > 255 || ...)
what about just making something like:
#define MAX_DISKS 255
...
int src_cnt = disks - 2;
...
BUG_ON(disks > MAX_DISKS || ...)
...
unsigned char coefs[MAX_DISKS];
?
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] async_pq: Remove VLA usage
2018-05-30 21:33 ` Kees Cook
@ 2018-05-30 22:04 ` Dan Williams
0 siblings, 0 replies; 7+ messages in thread
From: Dan Williams @ 2018-05-30 22:04 UTC (permalink / raw)
To: Kees Cook
Cc: Kyle Spiers, David Miller, ray.jui, linux-crypto,
Linux Kernel Mailing List, linux-raid, vkoul
On Wed, May 30, 2018 at 2:33 PM, Kees Cook <keescook@chromium.org> wrote:
> On Tue, May 29, 2018 at 3:40 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>> [ add Vinod's korg address ]
>>
>> On Tue, May 29, 2018 at 3:37 PM, Dan Williams <dan.j.williams@intel.com> wrote:
>>> [ adding linux-raid ]
>>>
>>> Apologies for the delay, the recent ping from Kees made me take a closer look.
>>>
>>> On Sat, May 5, 2018 at 12:58 AM, Kyle Spiers <ksspiers@google.com> wrote:
>>>> In the quest to remove VLAs from the kernel[1], this moves the
>>>> allocation of coefs and blocks from the stack to being kmalloc()ed.
>>>>
>>>> [1] https://lkml.org/lkml/2018/3/7/621
>>>>
>>>> Signed-off-by: Kyle Spiers <ksspiers@google.com>
>>>> ---
>>>> Forgot to add slab.h
>>>> ---
>>>> crypto/async_tx/async_pq.c | 18 ++++++++++++++----
>>>> crypto/async_tx/raid6test.c | 9 ++++++++-
>>>> 2 files changed, 22 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c
>>>> index 56bd612927ab..af1912313a23 100644
>>>> --- a/crypto/async_tx/async_pq.c
>>>> +++ b/crypto/async_tx/async_pq.c
>>>> @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks,
>>>> (src_cnt <= dma_maxpq(device, 0) ||
>>>> dma_maxpq(device, DMA_PREP_CONTINUE) > 0) &&
>>>> is_dma_pq_aligned(device, offset, 0, len)) {
>>>> - struct dma_async_tx_descriptor *tx;
>>>> + struct dma_async_tx_descriptor *tx = NULL;
>>>> enum dma_ctrl_flags dma_flags = 0;
>>>> - unsigned char coefs[src_cnt];
>>>> + unsigned char *coefs;
>>> At a minimum this needs to be GFP_NOIO since raid may be in the
>>> page-reclaim path.
>>>
>>> However, I think it may be better to allocate this with the rest of
>>> the stripe resources and pass it in as a scratch buffer. See the usage
>>> / implementation of scribble_alloc() in drivers/md/raid5.c.
>
> Given this:
>
> int src_cnt = disks - 2;
> ...
> BUG_ON(disks > 255 || ...)
>
> what about just making something like:
>
> #define MAX_DISKS 255
> ...
> int src_cnt = disks - 2;
> ...
> BUG_ON(disks > MAX_DISKS || ...)
> ...
> unsigned char coefs[MAX_DISKS];
>
> ?
Yeah, we were already potentially suffering a value that large on the
stack in a max config case anyway with the VLA. Looks ok to me.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-05-30 22:04 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-05-05 7:58 [PATCH v2] async_pq: Remove VLA usage Kyle Spiers
2018-05-10 20:57 ` Kees Cook
2018-05-29 22:24 ` Kees Cook
2018-05-29 22:37 ` Dan Williams
2018-05-29 22:40 ` Dan Williams
2018-05-30 21:33 ` Kees Cook
2018-05-30 22:04 ` Dan Williams
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