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xen: Prevent buffer overflow in privcmd ioctl

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commit 42d8644bd77dd2d747e004e367cb0c895a606f39 upstream.

The "call" variable comes from the user in privcmd_ioctl_hypercall().
It's an offset into the hypercall_page[] which has (PAGE_SIZE / 32)
elements.  We need to put an upper bound on it to prevent an out of
bounds access.

Cc: stable@vger.kernel.org
Fixes: 1246ae0bb9 ("xen: add variable hypercall caller")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Carpenter 2019-04-04 18:12:17 +03:00 • committed by Greg Kroah-Hartman
parent 442ebc6852
commit c082a57d41
1 changed files with 3 additions and 0 deletions
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3
arch/x86/include/asm/xen/hypercall.h
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@ -215,6 +215,9 @@ privcmd_call(unsigned call,
__HYPERCALL_DECLS;
__HYPERCALL_5ARG(a1, a2, a3, a4, a5);
if (call >= PAGE_SIZE / sizeof(hypercall_page[0]))
return -EINVAL;
stac();
asm volatile(CALL_NOSPEC
: __HYPERCALL_5PARAM