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SubjectRe: [PATCH] infiniband: core: fix information leak to userland
On Wed, Nov 10, 2010 at 16:01 -0800, Roland Dreier wrote:
> > Structure ib_uverbs_qp_attr is copied to userland with allmost all
> > fields uninitialized (140 bytes on x86). It leads to leaking of
> > contents of kernel stack memory.
>
> I don't think most of the fields are uninitialized... we have:
>
> memset(&qp_attr, 0, sizeof qp_attr);
>
> and then later on,
>
> ib_copy_qp_attr_to_user(&resp, &qp_attr);

Uh, sorry, I was over-pessimistic here...

> which actually does initialize almost all of the fields in resp. The
> things that are missing are clearing out the reserved fields in the
> structures, and also resp.qp_state never gets set.
>
> I would suggest adding code to clear the reserved fields of structures
> to ib_copy_qp_attr_to_user() and ib_copy_ah_attr_to_user(), since this
> will fix what looks to be the same problem in ucma_init_qp_attr() (in
> drivers/infiniband/core/ucma.c).


Also part of grh field and ib_uverbs_ah_attr->reserved. How do you see
this variant of zeroing? (I don't know whether these fields may be
needed for another callers.)

diff --git a/drivers/infiniband/core/ucm.c
b/drivers/infiniband/core/ucm.c
index 08f948d..f7256f3 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -629,6 +629,7 @@ static ssize_t ib_ucm_init_qp_attr(struct ib_ucm_file *file,
if (result)
goto out;

+ resp.qp_state = 0;
ib_copy_qp_attr_to_user(&resp, &qp_attr);

if (copy_to_user((void __user *)(unsigned long)cmd.response,
diff --git a/drivers/infiniband/core/ucma.c
b/drivers/infiniband/core/ucma.c
index ca12acf..07fd247 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -842,6 +842,7 @@ static ssize_t ucma_init_qp_attr(struct ucma_file *file,
if (ret)
goto out;

+ resp.qp_state = 0;
ib_copy_qp_attr_to_user(&resp, &qp_attr);
if (copy_to_user((void __user *)(unsigned long)cmd.response,
&resp, sizeof(resp)))
diff --git a/drivers/infiniband/core/uverbs_marshall.c
b/drivers/infiniband/core/uverbs_marshall.c
index 5440da0..cceaf33 100644
--- a/drivers/infiniband/core/uverbs_marshall.c
+++ b/drivers/infiniband/core/uverbs_marshall.c
@@ -35,6 +35,7 @@
void ib_copy_ah_attr_to_user(struct ib_uverbs_ah_attr *dst, struct ib_ah_attr *src)
{
+ memset(&dst->grh, 0, sizeof(dst->grh));
memcpy(dst->grh.dgid, src->grh.dgid.raw, sizeof src->grh.dgid);
dst->grh.flow_label = src->grh.flow_label;
dst->grh.sgid_index = src->grh.sgid_index;
@@ -46,6 +47,7 @@ void ib_copy_ah_attr_to_user(struct ib_uverbs_ah_attr *dst,
dst->static_rate = src->static_rate;
dst->is_global = src->ah_flags & IB_AH_GRH ? 1 : 0;
dst->port_num = src->port_num;
+ dst->reserved = 0;
}
EXPORT_SYMBOL(ib_copy_ah_attr_to_user);

@@ -83,6 +85,7 @@ void ib_copy_qp_attr_to_user(struct ib_uverbs_qp_attr *dst,
dst->rnr_retry = src->rnr_retry;
dst->alt_port_num = src->alt_port_num;
dst->alt_timeout = src->alt_timeout;
+ memset(dst->reserved, 0, sizeof(dst->reserved));
}
EXPORT_SYMBOL(ib_copy_qp_attr_to_user);

--
Vasiliy

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