Hi Peter, Please, see my comments below... On Fri, Jun 26, 2020 at 10:30:37AM +0300, Peter Ujfalusi wrote: > > > On 24/06/2020 20.12, Gustavo A. R. Silva wrote: > > Hi Vinod, > > > > On 6/24/20 00:55, Vinod Koul wrote: > >> On 19-06-20, 17:43, Gustavo A. R. Silva wrote: > >>> Make use of the struct_size() helper instead of an open-coded version > >>> in order to avoid any potential type mistakes. > >>> > >>> This code was detected with the help of Coccinelle and, audited and > >>> fixed manually. > >>> > >>> Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83 > >>> Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> > >>> --- > >>> drivers/dma/ti/k3-udma.c | 4 ++-- > >>> 1 file changed, 2 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c > >>> index 0d5fb154b8e2..411c54b86ba8 100644 > >>> --- a/drivers/dma/ti/k3-udma.c > >>> +++ b/drivers/dma/ti/k3-udma.c > >>> @@ -2209,7 +2209,7 @@ udma_prep_slave_sg_pkt(struct udma_chan *uc, struct scatterlist *sgl, > >>> u32 ring_id; > >>> unsigned int i; > >>> > >>> - d = kzalloc(sizeof(*d) + sglen * sizeof(d->hwdesc[0]), GFP_NOWAIT); > >>> + d = kzalloc(struct_size(d, hwdesc, sglen), GFP_NOWAIT); > >> > >> struct_size() is a * b + c but here we need, a + b * c.. the trailing > >> struct is N times here.. > >> > > > > struct_size() works exactly as expected in this case. :) > > Please, see: > > > > include/linux/overflow.h:314: > > 314 #define struct_size(p, member, count) \ > > 315 __ab_c_size(count, \ > > 316 sizeof(*(p)->member) + __must_be_array((p)->member),\ > > 317 sizeof(*(p))) > > True, struct_size is for this sort of things. > > Acked-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> > > While looking it up in include/linux/overflow.h I have noticed your > commit in linux-next, which adds flex_array_size() > > The example in the commit message contradicts with what the helper There is no contradiction here. > does imho. To be correct it should have been: > > struct something { > size_t count; > struct foo items[]; > }; > > - struct something *instance; > + struct something instance; > > - instance = kmalloc(struct_size(instance, items, count), GFP_KERNEL); > + instance.items = kmalloc(struct_size(instance, items, count), GFP_KERNEL); > instance->count = count; > memcpy(instance->items, src, flex_array_size(instance, items, instance->count)); > This is all wrong. Please, double check how struct_size() works. Thanks -- Gustavo > >>> if (!d) > >>> return NULL; > >>> > >>> @@ -2525,7 +2525,7 @@ udma_prep_dma_cyclic_pkt(struct udma_chan *uc, dma_addr_t buf_addr, > >>> if (period_len >= SZ_4M) > >>> return NULL; > >>> > >>> - d = kzalloc(sizeof(*d) + periods * sizeof(d->hwdesc[0]), GFP_NOWAIT); > >>> + d = kzalloc(struct_size(d, hwdesc, periods), GFP_NOWAIT); > >>> if (!d) > >>> return NULL; > >>> > >>> -- > >>> 2.27.0 > >> > > - Péter > > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki >
