From d6b7eaeb03421139e32800324ef04ab50bba886d Mon Sep 17 00:00:00 2001
From: Zhen Lei <thunder.leizhen@huawei.com>
Date: Wed, 9 Mar 2016 14:08:38 -0800
Subject: [PATCH] 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 <thunder.leizhen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/dma-mapping.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 75857cda38e98..728ef074602a6 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);
--
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