[PATCH] xen/arm: Fix the issue in cmp_mmio_handler used in find_mmio_handler

[PATCH] xen/arm: Fix the issue in cmp_mmio_handler used in find_mmio_handler

[Bhupinder Thakur]

This function returns true/false based on whether the key value
is in the range (start, start+size). However, it should check against
(start, start+size-1) because start+size falls outside the range.

This resulted in returning a wrong mmio_handler for a given mmio address which
happened to be start+size.

Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org>
---
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien.grall@arm.com>

 xen/arch/arm/io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
index e216128..c748d8f 100644
--- a/xen/arch/arm/io.c
+++ b/xen/arch/arm/io.c
@@ -79,7 +79,7 @@ static int cmp_mmio_handler(const void *key, const void *elem)
     if ( handler0->addr < handler1->addr )
         return -1;
 
-    if ( handler0->addr > (handler1->addr + handler1->size) )
+    if ( handler0->addr >= (handler1->addr + handler1->size) )
         return 1;
 
     return 0;
-- 
2.7.4


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Re: [PATCH] xen/arm: Fix the issue in cmp_mmio_handler used in find_mmio_handler

[Julien Grall]

Hi Bhupinder,

Good catch!

On 09/26/2017 11:45 PM, Bhupinder Thakur wrote:
> This function returns true/false based on whether the key value
> is in the range (start, start+size). However, it should check against
> (start, start+size-1) because start+size falls outside the range.
> 
> This resulted in returning a wrong mmio_handler for a given mmio address which
> happened to be start+size.

It would be nice if you can add the offending commit in the message. I 
think:

8047e09 "xen/arm: io: Use binary search for mmio handler lookup".

> Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org > ---
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien.grall@arm.com>

I think it should be backported up to Xen 4.8.

Cheers,

>   xen/arch/arm/io.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
> index e216128..c748d8f 100644
> --- a/xen/arch/arm/io.c
> +++ b/xen/arch/arm/io.c
> @@ -79,7 +79,7 @@ static int cmp_mmio_handler(const void *key, const void *elem)
>       if ( handler0->addr < handler1->addr )
>           return -1;
>   
> -    if ( handler0->addr > (handler1->addr + handler1->size) )
> +    if ( handler0->addr >= (handler1->addr + handler1->size) )
>           return 1;
>   
>       return 0;
> 

-- 
Julien Grall

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