| Message ID | 20220923202822.2667581-9-keescook@chromium.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | slab: Introduce kmalloc_size_roundup() | expand |
Am 23.09.22 um 22:28 schrieb Kees Cook: > 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: Sumit Semwal <sumit.semwal@linaro.org> > Cc: "Christian König" <christian.koenig@amd.com> > Cc: linux-media@vger.kernel.org > Cc: dri-devel@lists.freedesktop.org > Cc: linaro-mm-sig@lists.linaro.org > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Christian König <christian.koenig@amd.com> > --- > drivers/dma-buf/dma-resv.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c > index 205acb2c744d..5b0a4b8830ff 100644 > --- a/drivers/dma-buf/dma-resv.c > +++ b/drivers/dma-buf/dma-resv.c > @@ -98,12 +98,17 @@ static void dma_resv_list_set(struct dma_resv_list *list, > static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences) > { > struct dma_resv_list *list; > + size_t size; > > - list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL); > + /* Round up to the next kmalloc bucket size. */ > + size = kmalloc_size_roundup(struct_size(list, table, max_fences)); > + > + list = kmalloc(size, GFP_KERNEL); > if (!list) > return NULL; > > - list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) / > + /* Given the resulting bucket size, recalculated max_fences. */ > + list->max_fences = (size - offsetof(typeof(*list), table)) / > sizeof(*list->table); > > return list;
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 205acb2c744d..5b0a4b8830ff 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -98,12 +98,17 @@ static void dma_resv_list_set(struct dma_resv_list *list, static struct dma_resv_list *dma_resv_list_alloc(unsigned int max_fences) { struct dma_resv_list *list; + size_t size; - list = kmalloc(struct_size(list, table, max_fences), GFP_KERNEL); + /* Round up to the next kmalloc bucket size. */ + size = kmalloc_size_roundup(struct_size(list, table, max_fences)); + + list = kmalloc(size, GFP_KERNEL); if (!list) return NULL; - list->max_fences = (ksize(list) - offsetof(typeof(*list), table)) / + /* Given the resulting bucket size, recalculated max_fences. */ + list->max_fences = (size - offsetof(typeof(*list), table)) / sizeof(*list->table); return list;
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: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/dma-buf/dma-resv.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)