diff mbox series

[03/12] net: ipa: Proactively round up to kmalloc bucket size

Message ID 20220922031013.2150682-4-keescook@chromium.org (mailing list archive)
State Not Applicable
Delegated to: Johannes Berg
Headers show
Series slab: Introduce kmalloc_size_roundup() | expand

Commit Message

Kees Cook Sept. 22, 2022, 3:10 a.m. UTC
Instead of discovering the kmalloc bucket size _after_ allocation, round
up proactively so the allocation is explicitly made for the full size,
allowing the compiler to correctly reason about the resulting size of
the buffer through the existing __alloc_size() hint.

Cc: Alex Elder <elder@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/net/ipa/gsi_trans.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Alex Elder Sept. 22, 2022, 1:45 p.m. UTC | #1
On 9/21/22 10:10 PM, Kees Cook wrote:
> Instead of discovering the kmalloc bucket size _after_ allocation, round
> up proactively so the allocation is explicitly made for the full size,
> allowing the compiler to correctly reason about the resulting size of
> the buffer through the existing __alloc_size() hint.
> 
> Cc: Alex Elder <elder@kernel.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>   drivers/net/ipa/gsi_trans.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
> index 18e7e8c405be..cec968854dcf 100644
> --- a/drivers/net/ipa/gsi_trans.c
> +++ b/drivers/net/ipa/gsi_trans.c
> @@ -89,6 +89,7 @@ int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
>   			u32 max_alloc)
>   {
>   	void *virt;
> +	size_t allocate;

I don't care about this but the reverse Christmas tree
convention would put the "allocate" variable definition
above "virt".

Whether you fix that or not, this patch looks good to me.

Reviewed-by: Alex Elder <elder@linaro.org>

>   	if (!size)
>   		return -EINVAL;
> @@ -104,13 +105,15 @@ int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
>   	 * If there aren't enough entries starting at the free index,
>   	 * we just allocate free entries from the beginning of the pool.
>   	 */
> -	virt = kcalloc(count + max_alloc - 1, size, GFP_KERNEL);
> +	allocate = size_mul(count + max_alloc - 1, size);
> +	allocate = kmalloc_size_roundup(allocate);
> +	virt = kzalloc(allocate, GFP_KERNEL);
>   	if (!virt)
>   		return -ENOMEM;
>   
>   	pool->base = virt;
>   	/* If the allocator gave us any extra memory, use it */
> -	pool->count = ksize(pool->base) / size;
> +	pool->count = allocate / size;
>   	pool->free = 0;
>   	pool->max_alloc = max_alloc;
>   	pool->size = size;
Kees Cook Sept. 22, 2022, 3:57 p.m. UTC | #2
On Thu, Sep 22, 2022 at 08:45:19AM -0500, Alex Elder wrote:
> On 9/21/22 10:10 PM, Kees Cook wrote:
> > Instead of discovering the kmalloc bucket size _after_ allocation, round
> > up proactively so the allocation is explicitly made for the full size,
> > allowing the compiler to correctly reason about the resulting size of
> > the buffer through the existing __alloc_size() hint.
> > 
> > Cc: Alex Elder <elder@kernel.org>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Cc: Eric Dumazet <edumazet@google.com>
> > Cc: Jakub Kicinski <kuba@kernel.org>
> > Cc: Paolo Abeni <pabeni@redhat.com>
> > Cc: netdev@vger.kernel.org
> > Signed-off-by: Kees Cook <keescook@chromium.org>
> > ---
> >   drivers/net/ipa/gsi_trans.c | 7 +++++--
> >   1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
> > index 18e7e8c405be..cec968854dcf 100644
> > --- a/drivers/net/ipa/gsi_trans.c
> > +++ b/drivers/net/ipa/gsi_trans.c
> > @@ -89,6 +89,7 @@ int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
> >   			u32 max_alloc)
> >   {
> >   	void *virt;
> > +	size_t allocate;
> 
> I don't care about this but the reverse Christmas tree
> convention would put the "allocate" variable definition
> above "virt".

Oops, yes; thank you!

-Kees
diff mbox series

Patch

diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index 18e7e8c405be..cec968854dcf 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -89,6 +89,7 @@  int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
 			u32 max_alloc)
 {
 	void *virt;
+	size_t allocate;
 
 	if (!size)
 		return -EINVAL;
@@ -104,13 +105,15 @@  int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
 	 * If there aren't enough entries starting at the free index,
 	 * we just allocate free entries from the beginning of the pool.
 	 */
-	virt = kcalloc(count + max_alloc - 1, size, GFP_KERNEL);
+	allocate = size_mul(count + max_alloc - 1, size);
+	allocate = kmalloc_size_roundup(allocate);
+	virt = kzalloc(allocate, GFP_KERNEL);
 	if (!virt)
 		return -ENOMEM;
 
 	pool->base = virt;
 	/* If the allocator gave us any extra memory, use it */
-	pool->count = ksize(pool->base) / size;
+	pool->count = allocate / size;
 	pool->free = 0;
 	pool->max_alloc = max_alloc;
 	pool->size = size;