[PATCH] RDMA/bnxt_re: Prefer kcalloc over open coded arithmetic

[PATCH] RDMA/bnxt_re: Prefer kcalloc over open coded arithmetic

[Len Baker]

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

In this case this is not actually dynamic sizes: both sides of the
multiplication are constant values. However it is best to refactor this
anyway, just to keep the open-coded math idiom out of code.

So, use the purpose specific kcalloc() function instead of the argument
size * count in the kzalloc() function.

Also, remove the unnecessary initialization of the sqp_tbl variable
since it is set a few lines later.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/infiniband/hw/bnxt_re/ib_verbs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
index ea0054c60fbc..6fd4b87832b4 100644
--- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
+++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
@@ -1312,7 +1312,7 @@ static int bnxt_re_init_qp_attr(struct bnxt_re_qp *qp, struct bnxt_re_pd *pd,
 static int bnxt_re_create_shadow_gsi(struct bnxt_re_qp *qp,
 				     struct bnxt_re_pd *pd)
 {
-	struct bnxt_re_sqp_entries *sqp_tbl = NULL;
+	struct bnxt_re_sqp_entries *sqp_tbl;
 	struct bnxt_re_dev *rdev;
 	struct bnxt_re_qp *sqp;
 	struct bnxt_re_ah *sah;
@@ -1320,7 +1320,7 @@ static int bnxt_re_create_shadow_gsi(struct bnxt_re_qp *qp,

 	rdev = qp->rdev;
 	/* Create a shadow QP to handle the QP1 traffic */
-	sqp_tbl = kzalloc(sizeof(*sqp_tbl) * BNXT_RE_MAX_GSI_SQP_ENTRIES,
+	sqp_tbl = kcalloc(BNXT_RE_MAX_GSI_SQP_ENTRIES, sizeof(*sqp_tbl),
 			  GFP_KERNEL);
 	if (!sqp_tbl)
 		return -ENOMEM;
--
2.25.1

Re: [PATCH] RDMA/bnxt_re: Prefer kcalloc over open coded arithmetic

[Leon Romanovsky]

On Sun, Sep 05, 2021 at 10:18:12AM +0200, Len Baker wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> In this case this is not actually dynamic sizes: both sides of the
> multiplication are constant values. However it is best to refactor this
> anyway, just to keep the open-coded math idiom out of code.
> 
> So, use the purpose specific kcalloc() function instead of the argument
> size * count in the kzalloc() function.
> 
> Also, remove the unnecessary initialization of the sqp_tbl variable
> since it is set a few lines later.
> 
> [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Signed-off-by: Len Baker <len.baker@gmx.com>
> ---
>  drivers/infiniband/hw/bnxt_re/ib_verbs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>

Re: [PATCH] RDMA/bnxt_re: Prefer kcalloc over open coded arithmetic

[Selvin Xavier]

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On Sun, Sep 5, 2021 at 3:51 PM Leon Romanovsky <leon@kernel.org> wrote:
>
> On Sun, Sep 05, 2021 at 10:18:12AM +0200, Len Baker wrote:
> > As noted in the "Deprecated Interfaces, Language Features, Attributes,
> > and Conventions" documentation [1], size calculations (especially
> > multiplication) should not be performed in memory allocator (or similar)
> > function arguments due to the risk of them overflowing. This could lead
> > to values wrapping around and a smaller allocation being made than the
> > caller was expecting. Using those allocations could lead to linear
> > overflows of heap memory and other misbehaviors.
> >
> > In this case this is not actually dynamic sizes: both sides of the
> > multiplication are constant values. However it is best to refactor this
> > anyway, just to keep the open-coded math idiom out of code.
> >
> > So, use the purpose specific kcalloc() function instead of the argument
> > size * count in the kzalloc() function.
> >
> > Also, remove the unnecessary initialization of the sqp_tbl variable
> > since it is set a few lines later.
> >
> > [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> >
> > Signed-off-by: Len Baker <len.baker@gmx.com>
> > ---
> >  drivers/infiniband/hw/bnxt_re/ib_verbs.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
>
> Thanks,
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>

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Re: [PATCH] RDMA/bnxt_re: Prefer kcalloc over open coded arithmetic

[Jason Gunthorpe]

On Sun, Sep 05, 2021 at 10:18:12AM +0200, Len Baker wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> In this case this is not actually dynamic sizes: both sides of the
> multiplication are constant values. However it is best to refactor this
> anyway, just to keep the open-coded math idiom out of code.
> 
> So, use the purpose specific kcalloc() function instead of the argument
> size * count in the kzalloc() function.
> 
> Also, remove the unnecessary initialization of the sqp_tbl variable
> since it is set a few lines later.
> 
> [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Signed-off-by: Len Baker <len.baker@gmx.com>
> Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
> Acked-by: Selvin Xavier <selvin.xavier@broadcom.com>
> ---
>  drivers/infiniband/hw/bnxt_re/ib_verbs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied to for-rc, thanks

Jason