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 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)); If I'm not mistaken.. > > 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
