In case of error while accessing to userspace memory,
function nes_create_qp() returns NULL instead of an error
code wrapped through ERR_PTR().
But NULL is not expected by ib_uverbs_create_qp(), as it
check for error with IS_ERR().
As page 0 is likely not mapped, it is going to trigger an
Oops when the kernel will try to dereference NULL pointer
to access to struct ib_qp's fields.
In some rare cases, page 0 could be mapped by userspace,
which could turn this bug to a vulnerability that could be
exploited: the function pointers in struct ib_device will be under
userspace total control.
This was caught when using spatch (aka. coccinelle)
to rewrite calls to ib_copy_{from,to}_udata().
Link: https://www.gitorious.org/opteya/ib-hw-nes-create-qp-null
Link: https://www.gitorious.org/opteya/coccib/source/75ebf2c1033c64c1d81df13e4ae44ee99c989eba:ib_copy_udata.cocci
Link: http://marc.info/?i=cover.1394485254.git.ydroneaud@xxxxxxxxxx
Cc: Faisal Latif <faisal.latif@xxxxxxxxx>
Cc: Tatyana E. Nikolova <tatyana.e.nikolova@xxxxxxxxx>
Cc: Julia Lawall <julia.lawall@xxxxxxx>
Cc: cocci@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
---
drivers/infiniband/hw/nes/nes_verbs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/infiniband/hw/nes/nes_verbs.c b/drivers/infiniband/hw/nes/nes_verbs.c
index 8308e3634767..eb624611f94b 100644
--- a/drivers/infiniband/hw/nes/nes_verbs.c
+++ b/drivers/infiniband/hw/nes/nes_verbs.c
@@ -1186,7 +1186,7 @@ static struct ib_qp *nes_create_qp(struct ib_pd *ibpd,
nes_free_resource(nesadapter, nesadapter->allocated_qps, qp_num);
kfree(nesqp->allocated_buffer);
nes_debug(NES_DBG_QP, "ib_copy_from_udata() Failed \n");
- return NULL;
+ return ERR_PTR(-EFAULT);
}
if (req.user_wqe_buffers) {
virt_wqs = 1;
--
1.8.5.3
--
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