commit 9d194d1025 upstream.
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: 75ebf2c103:ib_copy_udata.cocci
Link: http://marc.info/?i=cover.1394485254.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
64900cd67c