| Message ID | 20190404151217.GA22334@kadam (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 42d8644bd77dd2d747e004e367cb0c895a606f39 |
| Headers | show |
| Series | xen: Prevent buffer overflow in privcmd ioctl | expand |
On 4/4/19 11:12 AM, Dan Carpenter wrote: > 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. > > Fixes: 1246ae0bb992 ("xen: add variable hypercall caller") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> I am also adding stable@vger.kernel.org -boris > --- > arch/x86/include/asm/xen/hypercall.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h > index de6f0d59a24f..2863c2026655 100644 > --- a/arch/x86/include/asm/xen/hypercall.h > +++ b/arch/x86/include/asm/xen/hypercall.h > @@ -206,6 +206,9 @@ xen_single_call(unsigned int call, > __HYPERCALL_DECLS; > __HYPERCALL_5ARG(a1, a2, a3, a4, a5); > > + if (call >= PAGE_SIZE / sizeof(hypercall_page[0])) > + return -EINVAL; > + > asm volatile(CALL_NOSPEC > : __HYPERCALL_5PARAM > : [thunk_target] "a" (&hypercall_page[call])
On 04/04/2019 17:12, Dan Carpenter wrote: > 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. > > Fixes: 1246ae0bb992 ("xen: add variable hypercall caller") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Pushed to xen/tip.git for-linus-5.1b Juergen
diff --git a/arch/x86/include/asm/xen/hypercall.h b/arch/x86/include/asm/xen/hypercall.h index de6f0d59a24f..2863c2026655 100644 --- a/arch/x86/include/asm/xen/hypercall.h +++ b/arch/x86/include/asm/xen/hypercall.h @@ -206,6 +206,9 @@ xen_single_call(unsigned int call, __HYPERCALL_DECLS; __HYPERCALL_5ARG(a1, a2, a3, a4, a5); + if (call >= PAGE_SIZE / sizeof(hypercall_page[0])) + return -EINVAL; + asm volatile(CALL_NOSPEC : __HYPERCALL_5PARAM : [thunk_target] "a" (&hypercall_page[call])
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. Fixes: 1246ae0bb992 ("xen: add variable hypercall caller") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- arch/x86/include/asm/xen/hypercall.h | 3 +++ 1 file changed, 3 insertions(+)