[PATCH v3 0/9] slab: provide and use krealloc_array()
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.
v1 -> v2: - added a kernel doc for krealloc_array() - mentioned krealloc et al in the docs - collected review tags
v2 -> v3: - add a patch improving krealloc()'s kerneldoc - fix a typo - improve .rst doc - tweak line breaks
Bartosz Golaszewski (9): mm: slab: clarify krealloc()'s behavior with __GFP_ZERO 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()
Documentation/core-api/memory-allocation.rst | 4 ++++ drivers/dma-buf/sync_file.c | 3 +-- 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 | 18 ++++++++++++++++++ mm/slab_common.c | 6 +++--- sound/core/pcm_lib.c | 4 ++-- 10 files changed, 36 insertions(+), 13 deletions(-)
From: Bartosz Golaszewski bgolaszewski@baylibre.com
__GFP_ZERO is ignored by krealloc() (unless we fall-back to kmalloc() path, in which case it's honored). Point that out in the kerneldoc.
Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com --- mm/slab_common.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/slab_common.c b/mm/slab_common.c index f9ccd5dc13f3..d6df73f79204 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1091,9 +1091,9 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size, * @flags: the type of memory to allocate. * * The contents of the object pointed to are preserved up to the - * lesser of the new and old sizes. If @p is %NULL, krealloc() - * behaves exactly like kmalloc(). If @new_size is 0 and @p is not a - * %NULL pointer, the object pointed to is freed. + * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). + * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size + * is 0 and @p is not a %NULL pointer, the object pointed to is freed. * * Return: pointer to the allocated memory or %NULL in case of error */
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.
While at it: add some documentation regarding krealloc.
Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com Acked-by: Vlastimil Babka vbabka@suse.cz --- Documentation/core-api/memory-allocation.rst | 4 ++++ include/linux/slab.h | 18 ++++++++++++++++++ 2 files changed, 22 insertions(+)
diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst index 4446a1ac36cc..5954ddf6ee13 100644 --- a/Documentation/core-api/memory-allocation.rst +++ b/Documentation/core-api/memory-allocation.rst @@ -147,6 +147,10 @@ The address of a chunk allocated with `kmalloc` is aligned to at least ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of two, the alignment is also guaranteed to be at least the respective size.
+Chunks allocated with kmalloc() can be resized with krealloc(). Similarly +to kmalloc_array(): a helper for resizing arrays is provided in the form of +krealloc_array(). + For large allocations you can use vmalloc() and vzalloc(), or directly request pages from the page allocator. The memory allocated by `vmalloc` and related functions is not physically contiguous. diff --git a/include/linux/slab.h b/include/linux/slab.h index dd6897f62010..be4ba5867ac5 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -592,6 +592,24 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags) return __kmalloc(bytes, flags); }
+/** + * krealloc_array - reallocate memory for an array. + * @p: pointer to the memory chunk to reallocate + * @new_n: new number of elements to alloc + * @new_size: new size of a single member of the array + * @flags: the type of memory to allocate (see kmalloc) + */ +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.
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 Reviewed-by: Takashi Iwai tiwai@suse.de --- sound/core/pcm_lib.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c index bda3514c7b2d..b7e3d8f44511 100644 --- a/sound/core/pcm_lib.c +++ b/sound/core/pcm_lib.c @@ -1129,8 +1129,8 @@ int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond, if (constrs->rules_num >= constrs->rules_all) { struct snd_pcm_hw_rule *new; unsigned int new_rules = constrs->rules_all + 16; - new = krealloc(constrs->rules, new_rules * sizeof(*c), - GFP_KERNEL); + new = krealloc_array(constrs->rules, new_rules, + sizeof(*c), GFP_KERNEL); if (!new) { va_end(args); return -ENOMEM;
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: Michael S. Tsirkin mst@redhat.com --- drivers/vhost/vringh.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index 8bd8b403f087..08a0e1c842df 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -198,7 +198,8 @@ static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
flag = (iov->max_num & VRINGH_IOV_ALLOCATED); if (flag) - new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp); + new = krealloc_array(iov->iov, new_num, + sizeof(struct iovec), gfp); else { new = kmalloc_array(new_num, sizeof(struct iovec), gfp); if (new) {
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 Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com --- drivers/pinctrl/pinctrl-utils.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pinctrl/pinctrl-utils.c b/drivers/pinctrl/pinctrl-utils.c index f2bcbf62c03d..93df0d4c0a24 100644 --- a/drivers/pinctrl/pinctrl-utils.c +++ b/drivers/pinctrl/pinctrl-utils.c @@ -39,7 +39,7 @@ int pinctrl_utils_reserve_map(struct pinctrl_dev *pctldev, if (old_num >= new_num) return 0;
- new_map = krealloc(*map, sizeof(*new_map) * new_num, GFP_KERNEL); + new_map = krealloc_array(*map, new_num, sizeof(*new_map), GFP_KERNEL); if (!new_map) { dev_err(pctldev->dev, "krealloc(map) failed\n"); return -ENOMEM;
On Mon, Nov 9, 2020 at 12:07 PM Bartosz Golaszewski brgl@bgdev.pl 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 Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com
Reviewed-by: Linus Walleij linus.walleij@linaro.org
Yours, Linus Walleij
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: Borislav Petkov bp@suse.de --- drivers/edac/ghes_edac.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c index a918ca93e4f7..6d1ddecbf0da 100644 --- a/drivers/edac/ghes_edac.c +++ b/drivers/edac/ghes_edac.c @@ -207,8 +207,8 @@ static void enumerate_dimms(const struct dmi_header *dh, void *arg) if (!hw->num_dimms || !(hw->num_dimms % 16)) { struct dimm_info *new;
- new = krealloc(hw->dimms, (hw->num_dimms + 16) * sizeof(struct dimm_info), - GFP_KERNEL); + new = krealloc_array(hw->dimms, hw->num_dimms + 16, + sizeof(struct dimm_info), GFP_KERNEL); if (!new) { WARN_ON_ONCE(1); return;
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: Daniel Vetter daniel.vetter@ffwll.ch --- drivers/gpu/drm/drm_atomic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 58527f151984..09ad6a2ec17b 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -960,7 +960,8 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state, struct __drm_connnectors_state *c; int alloc = max(index + 1, config->num_connector);
- c = krealloc(state->connectors, alloc * sizeof(*state->connectors), GFP_KERNEL); + c = krealloc_array(state->connectors, alloc, + sizeof(*state->connectors), GFP_KERNEL); if (!c) return ERR_PTR(-ENOMEM);
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 --- drivers/hwtracing/intel_th/msu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c index 3a77551fb4fc..7d95242db900 100644 --- a/drivers/hwtracing/intel_th/msu.c +++ b/drivers/hwtracing/intel_th/msu.c @@ -2002,7 +2002,7 @@ nr_pages_store(struct device *dev, struct device_attribute *attr, }
nr_wins++; - rewin = krealloc(win, sizeof(*win) * nr_wins, GFP_KERNEL); + rewin = krealloc_array(win, nr_wins, sizeof(*win), GFP_KERNEL); if (!rewin) { kfree(win); return -ENOMEM;
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 | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index 5a5a1da01a00..20d9bddbb985 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -270,8 +270,7 @@ 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;
participants (2)
-
Bartosz Golaszewski -
Linus Walleij