| Message ID | 20210918104055.8444-1-len.baker@gmx.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | dmaengine: pxa_dma: Prefer struct_size over open coded arithmetic | expand |
On 9/18/21 05:40, 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. > > So, use the struct_size() helper to do the arithmetic instead of the > argument "size + count * size" in the kzalloc() function. > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/dma/pxa_dma.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c > index 4a2a796e348c..52d04641e361 100644 > --- a/drivers/dma/pxa_dma.c > +++ b/drivers/dma/pxa_dma.c > @@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc) > dma_addr_t dma; > int i; > > - sw_desc = kzalloc(sizeof(*sw_desc) + > - nb_hw_desc * sizeof(struct pxad_desc_hw *), > + sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), > GFP_NOWAIT); > if (!sw_desc) > return NULL; > -- > 2.25.1 >
On Mon, Sep 20, 2021 at 07:00:58PM -0500, Gustavo A. R. Silva wrote: > > > On 9/18/21 05:40, 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. > > > > So, use the struct_size() helper to do the arithmetic instead of the > > argument "size + count * size" in the kzalloc() function. > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments > > > > Signed-off-by: Len Baker <len.baker@gmx.com> > > Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> I'm taking this in my -next tree. Thanks -- Gustavo
diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c index 4a2a796e348c..52d04641e361 100644 --- a/drivers/dma/pxa_dma.c +++ b/drivers/dma/pxa_dma.c @@ -742,8 +742,7 @@ pxad_alloc_desc(struct pxad_chan *chan, unsigned int nb_hw_desc) dma_addr_t dma; int i; - sw_desc = kzalloc(sizeof(*sw_desc) + - nb_hw_desc * sizeof(struct pxad_desc_hw *), + sw_desc = kzalloc(struct_size(sw_desc, hw_desc, nb_hw_desc), GFP_NOWAIT); if (!sw_desc) return NULL;
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. So, use the struct_size() helper to do the arithmetic instead of the argument "size + count * size" in the kzalloc() function. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments Signed-off-by: Len Baker <len.baker@gmx.com> --- drivers/dma/pxa_dma.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) -- 2.25.1