From: Zhen Lei Date: Wed, 9 Mar 2016 22:08:38 +0000 (-0800) Subject: dma-mapping: avoid oops when parameter cpu_addr is null X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d6b7eaeb03421139e32800324ef04ab50bba886d;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git dma-mapping: avoid oops when parameter cpu_addr is null To keep consistent with kfree, which tolerate ptr is NULL. We do this because sometimes we may use goto statement, so that success and failure case can share parts of the code. But unfortunately, dma_free_coherent called with parameter cpu_addr is null will cause oops, such as showed below: Unable to handle kernel paging request at virtual address ffffffc020d3b2b8 pgd = ffffffc083a61000 [ffffffc020d3b2b8] *pgd=0000000000000000, *pud=0000000000000000 CPU: 4 PID: 1489 Comm: malloc_dma_1 Tainted: G O 4.1.12 #1 Hardware name: ARM64 (DT) PC is at __dma_free_coherent.isra.10+0x74/0xc8 LR is at __dma_free+0x9c/0xb0 Process malloc_dma_1 (pid: 1489, stack limit = 0xffffffc0837fc020) [...] Call trace: __dma_free_coherent.isra.10+0x74/0xc8 __dma_free+0x9c/0xb0 malloc_dma+0x104/0x158 [dma_alloc_coherent_mtmalloc] kthread+0xec/0xfc Signed-off-by: Zhen Lei Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 75857cda38e9..728ef074602a 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -386,7 +386,7 @@ static inline void dma_free_attrs(struct device *dev, size_t size, if (dma_release_from_coherent(dev, get_order(size), cpu_addr)) return; - if (!ops->free) + if (!ops->free || !cpu_addr) return; debug_dma_free_coherent(dev, size, cpu_addr, dma_handle);