| Message ID | 20201027121725.24660-1-brgl@bgdev.pl |
|---|---|
| Headers | show |
| Series | slab: provide and use krealloc_array() | expand |
Am 27.10.20 um 13:17 schrieb Bartosz Golaszewski: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > Use the helper that checks for overflows internally instead of manually > calculating the size of the new array. > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Acked-by: Christian König <christian.koenig@amd.com> > --- > drivers/dma-buf/sync_file.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c > index 5a5a1da01a00..2925ea03eef0 100644 > --- a/drivers/dma-buf/sync_file.c > +++ b/drivers/dma-buf/sync_file.c > @@ -270,8 +270,8 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, > fences[i++] = dma_fence_get(a_fences[0]); > > if (num_fences > i) { > - nfences = krealloc(fences, i * sizeof(*fences), > - GFP_KERNEL); > + nfences = krealloc_array(fences, i, > + sizeof(*fences), GFP_KERNEL); > if (!nfences) > goto err; >
On Tue, Oct 27, 2020 at 5:50 PM Joe Perches <joe@perches.com> wrote: > > On Tue, 2020-10-27 at 11:28 -0400, Michael S. Tsirkin wrote: > > On Tue, Oct 27, 2020 at 01:17:20PM +0100, Bartosz Golaszewski wrote: > > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > > > Use the helper that checks for overflows internally instead of manually > > > calculating the size of the new array. > > > > > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > No problem with the patch, it does introduce some symmetry in the code. > > Perhaps more symmetry by using kmemdup > --- > drivers/vhost/vringh.c | 23 ++++++++++------------- > 1 file changed, 10 insertions(+), 13 deletions(-) > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index 8bd8b403f087..99222a3651cd 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -191,26 +191,23 @@ static int move_to_indirect(const struct vringh *vrh, > static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) > { > struct kvec *new; > - unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; > + size_t new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; > + size_t size; > > if (new_num < 8) > new_num = 8; > > - flag = (iov->max_num & VRINGH_IOV_ALLOCATED); > - if (flag) > - new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); > - else { > - new = kmalloc_array(new_num, sizeof(struct iovec), gfp); > - if (new) { > - memcpy(new, iov->iov, > - iov->max_num * sizeof(struct iovec)); > - flag = VRINGH_IOV_ALLOCATED; > - } > - } > + if (unlikely(check_mul_overflow(new_num, sizeof(struct iovec), &size))) > + return -ENOMEM; > + The whole point of using helpers such as kmalloc_array() is not doing these checks manually. Bartosz > + if (iov->max_num & VRINGH_IOV_ALLOCATED) > + new = krealloc(iov->iov, size, gfp); > + else > + new = kmemdup(iov->iov, size, gfp); > if (!new) > return -ENOMEM; > iov->iov = new; > - iov->max_num = (new_num | flag); > + iov->max_num = new_num | VRINGH_IOV_ALLOCATED; > return 0; > } > > >
On Tue, Oct 27, 2020 at 6:08 PM Joe Perches <joe@perches.com> wrote: > > On Tue, 2020-10-27 at 17:58 +0100, Bartosz Golaszewski wrote: > > On Tue, Oct 27, 2020 at 5:50 PM Joe Perches <joe@perches.com> wrote: > > > > > > On Tue, 2020-10-27 at 11:28 -0400, Michael S. Tsirkin wrote: > > > > On Tue, Oct 27, 2020 at 01:17:20PM +0100, Bartosz Golaszewski wrote: > > > > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > > > > > > > Use the helper that checks for overflows internally instead of manually > > > > > calculating the size of the new array. > > > > > > > > > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > > > > > > > No problem with the patch, it does introduce some symmetry in the code. > > > > > > Perhaps more symmetry by using kmemdup > > > --- > > > drivers/vhost/vringh.c | 23 ++++++++++------------- > > > 1 file changed, 10 insertions(+), 13 deletions(-) > > > > > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > > > index 8bd8b403f087..99222a3651cd 100644 > > > --- a/drivers/vhost/vringh.c > > > +++ b/drivers/vhost/vringh.c > > > @@ -191,26 +191,23 @@ static int move_to_indirect(const struct vringh *vrh, > > > static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp) > > > { > > > struct kvec *new; > > > - unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; > > > + size_t new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2; > > > + size_t size; > > > > > > if (new_num < 8) > > > new_num = 8; > > > > > > - flag = (iov->max_num & VRINGH_IOV_ALLOCATED); > > > - if (flag) > > > - new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); > > > - else { > > > - new = kmalloc_array(new_num, sizeof(struct iovec), gfp); > > > - if (new) { > > > - memcpy(new, iov->iov, > > > - iov->max_num * sizeof(struct iovec)); > > > - flag = VRINGH_IOV_ALLOCATED; > > > - } > > > - } > > > + if (unlikely(check_mul_overflow(new_num, sizeof(struct iovec), &size))) > > > + return -ENOMEM; > > > + > > > > The whole point of using helpers such as kmalloc_array() is not doing > > these checks manually. > > Tradeoffs for in readability for overflow and not mistyping or doing > the multiplication of iov->max_num * sizeof(struct iovec) twice. > It's out of scope for this series - I want to add users for krealloc_array(), not refactor code I don't really know. If the maintainer of this bit objects, it can be dropped. > Just fyi: > > the realloc doesn't do a multiplication overflow test as written so the > suggestion is slightly more resistant to defect. > I'm not sure what your point is. I used krealloc_array() exactly for this reason - to add the overflow test. BTW I suppose kmalloc_array() here can be replaced with krealloc_array() if the original pointer is NULL the first time it's called. Bartosz
On 10/27/20 1:17 PM, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > When allocating an array of elements, users should check for > multiplication overflow or preferably use one of the provided helpers > like: kmalloc_array(). > > There's no krealloc_array() counterpart but there are many users who use > regular krealloc() to reallocate arrays. Let's provide an actual > krealloc_array() implementation. > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> Makes sense. Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > include/linux/slab.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index dd6897f62010..0e6683affee7 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -592,6 +592,17 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags) > return __kmalloc(bytes, flags); > } > > +static __must_check inline void * > +krealloc_array(void *p, size_t new_n, size_t new_size, gfp_t flags) > +{ > + size_t bytes; > + > + if (unlikely(check_mul_overflow(new_n, new_size, &bytes))) > + return NULL; > + > + return krealloc(p, bytes, flags); > +} > + > /** > * kcalloc - allocate memory for an array. The memory is set to zero. > * @n: number of elements. >
On Tue, Oct 27, 2020 at 01:17:18PM +0100, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > When allocating an array of elements, users should check for > multiplication overflow or preferably use one of the provided helpers > like: kmalloc_array(). > > There's no krealloc_array() counterpart but there are many users who use > regular krealloc() to reallocate arrays. Let's provide an actual > krealloc_array() implementation. > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com> > --- > include/linux/slab.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index dd6897f62010..0e6683affee7 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -592,6 +592,17 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags) > return __kmalloc(bytes, flags); > } > Can you please add kernel-doc here and a word or two about this function to Documentation/core-api/memory-allocation.rst? > +static __must_check inline void * > +krealloc_array(void *p, size_t new_n, size_t new_size, gfp_t flags) > +{ > + size_t bytes; > + > + if (unlikely(check_mul_overflow(new_n, new_size, &bytes))) > + return NULL; > + > + return krealloc(p, bytes, flags); > +} > + > /** > * kcalloc - allocate memory for an array. The memory is set to zero. > * @n: number of elements. > -- > 2.29.1 > >
On Tue, Oct 27, 2020 at 1:17 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > Andy brought to my attention the fact that users allocating an array of > equally sized elements should check if the size multiplication doesn't > overflow. This is why we have helpers like kmalloc_array(). > > However we don't have krealloc_array() equivalent and there are many > users who do their own multiplication when calling krealloc() for arrays. > > This series provides krealloc_array() and uses it in a couple places. > > A separate series will follow adding devm_krealloc_array() which is > needed in the xilinx adc driver. The series: Acked-by: Linus Walleij <linus.walleij@linaro.org> I really like this. Yours, Linus Walleij
From: Bartosz Golaszewski <bgolaszewski@baylibre.com> Andy brought to my attention the fact that users allocating an array of equally sized elements should check if the size multiplication doesn't overflow. This is why we have helpers like kmalloc_array(). However we don't have krealloc_array() equivalent and there are many users who do their own multiplication when calling krealloc() for arrays. This series provides krealloc_array() and uses it in a couple places. A separate series will follow adding devm_krealloc_array() which is needed in the xilinx adc driver. Bartosz Golaszewski (8): mm: slab: provide krealloc_array() ALSA: pcm: use krealloc_array() vhost: vringh: use krealloc_array() pinctrl: use krealloc_array() edac: ghes: use krealloc_array() drm: atomic: use krealloc_array() hwtracing: intel: use krealloc_array() dma-buf: use krealloc_array() drivers/dma-buf/sync_file.c | 4 ++-- drivers/edac/ghes_edac.c | 4 ++-- drivers/gpu/drm/drm_atomic.c | 3 ++- drivers/hwtracing/intel_th/msu.c | 2 +- drivers/pinctrl/pinctrl-utils.c | 2 +- drivers/vhost/vringh.c | 3 ++- include/linux/slab.h | 11 +++++++++++ sound/core/pcm_lib.c | 4 ++-- 8 files changed, 23 insertions(+), 10 deletions(-)