Both the size parameter in the dma_alloc_from_[dev/global]_coherent() functions and the size field in the dma_coherent_mem structure are represented by a signed quantity, which makes it so that any comparisons between these two quantities is a signed comparison.

When a reserved memory region is larger than or equal to 2GB in size, this will cause the most significant bit to be set to 1, thus, treating the size as a negative number in signed comparisons.

This can result in allocation failures when an amount of memory that is strictly less than 2 GB is requested from this region. The allocation fails because the signed comparison to prevent from allocating more memory than what is in the region in __dma_alloc_from_coherent() evaluates to true since the size of the region is treated as a negative number, but the size of the request is treated as a positive number.

Thus, change the type of the size parameter in the allocation functions to an unsigned type, and change the type of the size field in the dma_coherent_mem structure to an unsigned type as well, as it does not make sense for sizes to be represented by signed quantities.

Fixes: ee7e5516be4f ("generic: per-device coherent dma allocator") Signed-off-by: Isaac J. Manjarres isaacm@codeaurora.org Cc: stable@vger.kernel.org --- include/linux/dma-mapping.h | 6 +++--- kernel/dma/coherent.c | 8 ++++---- 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index f7d1eea..06d446d 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -159,14 +159,14 @@ static inline int is_device_dma_capable(struct device *dev) * These three functions are only for dma allocator. * Don't use them in device drivers. */ -int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, +int dma_alloc_from_dev_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, void **ret); int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr);

int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, size_t size, int *ret);

-void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle); +void *dma_alloc_from_global_coherent(size_t size, dma_addr_t *dma_handle); int dma_release_from_global_coherent(int order, void *vaddr); int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr, size_t size, int *ret); @@ -176,7 +176,7 @@ int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr, #define dma_release_from_dev_coherent(dev, order, vaddr) (0) #define dma_mmap_from_dev_coherent(dev, vma, vaddr, order, ret) (0)

-static inline void *dma_alloc_from_global_coherent(ssize_t size, +static inline void *dma_alloc_from_global_coherent(size_t size, dma_addr_t *dma_handle) { return NULL; diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c index 29fd659..c671d5c 100644 --- a/kernel/dma/coherent.c +++ b/kernel/dma/coherent.c @@ -13,7 +13,7 @@ struct dma_coherent_mem { void *virt_base; dma_addr_t device_base; unsigned long pfn_base; - int size; + unsigned long size; unsigned long *bitmap; spinlock_t spinlock; bool use_dev_dma_pfn_offset; @@ -136,7 +136,7 @@ void dma_release_declared_memory(struct device *dev) EXPORT_SYMBOL(dma_release_declared_memory);

static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem, - ssize_t size, dma_addr_t *dma_handle) + size_t size, dma_addr_t *dma_handle) { int order = get_order(size); unsigned long flags; @@ -179,7 +179,7 @@ static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem, * Returns 0 if dma_alloc_coherent should continue with allocating from * generic memory areas, or !0 if dma_alloc_coherent should return @ret. */ -int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, +int dma_alloc_from_dev_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, void **ret) { struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); @@ -191,7 +191,7 @@ int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, return 1; }

-void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle) +void *dma_alloc_from_global_coherent(size_t size, dma_addr_t *dma_handle) { if (!dma_coherent_default_memory) return NULL;