Re: [Stable-review] [patch 31/38] ARM: 6891/1: prevent heapcorruption in OABI semtimedop

[Ben Hutchings]

On Thu, 2011-05-05 at 17:11 -0700, Greg KH wrote:
> 2.6.38-stable review patch.  If anyone has any objections, please let us know.
> 
> ------------------
> 
> From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
> 
> commit 0f22072ab50cac7983f9660d33974b45184da4f9 upstream.
> 
> When CONFIG_OABI_COMPAT is set, the wrapper for semtimedop does not
> bound the nsops argument.  A sufficiently large value will cause an
> integer overflow in allocation size, followed by copying too much data
> into the allocated buffer.  Fix this by restricting nsops to SEMOPM.
> Untested.
> 
> Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
> 
> ---
>  arch/arm/kernel/sys_oabi-compat.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/arch/arm/kernel/sys_oabi-compat.c
> +++ b/arch/arm/kernel/sys_oabi-compat.c
> @@ -311,7 +311,7 @@ asmlinkage long sys_oabi_semtimedop(int
>  	long err;
>  	int i;
>  
> -	if (nsops < 1)
> +	if (nsops < 1 || nsops > SEMOPM)
>  		return -EINVAL;

It's not that important, but the manual page says the error code should
E2BIG in the latter case.

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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