Re: [PATCH Bugfix v2 2/4] x86/xsaves: Define and use user_xstate_size for xstate size in signal context

[Dave Hansen]

On 04/21/2015 09:51 PM, Fenghua Yu wrote:
> +static int copy_to_user_xstate(void __user *buf_fx, struct xsave_struct *xsave)
> +{
...
> +			if (__copy_to_user(buf_fx + user_offset,
> +				     xsave + kernel_offset, size))
> +				return -1;
> +		}
> +	}
> +

0day found this, but I'm replying to the original thread.

> [   13.595511] BUG: KASan: out of bounds access in save_xstate_sig+0x1bf/0x470 at addr ffff880000184208
> [   13.596280] Read of size 8 by task init/1

copy_to_user_xstate() gets inlined in to save_xstate_sig().  The read
probably means that this was an access to 'xsave' since we are reading a
kernel structure out to userspace.

'xsave' is a 'struct xsave_struct *' and yet it's being incremented like
'buf_fx' which is a 'void *'.


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