Guenter Roeck
2022-Mar-27 05:38 UTC
[Nouveau] [PATCH] device: fix missing check on list iterator
On 3/26/22 22:31, Xiaomeng Tong wrote:> The bug is here: > lo = pstate->base.domain[domain->name]; > > The list iterator 'pstate' will point to a bogus position containing > HEAD if the list is empty or no element is found. This case should > be checked before any use of the iterator, otherwise it will lead > to a invalid memory access. > > To fix this bug, add an check. Use a new value 'iter' as the list > iterator, while use the old value 'pstate' as a dedicated variable > to point to the found element. > > Cc: stable at vger.kernel.org > Fixes: 9838366c1597d ("drm/nouveau/device: initial control object class, with pstate control methods") > Signed-off-by: Xiaomeng Tong <xiam0nd.tong at gmail.com> > --- > drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c b/drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c > index ce774579c89d..6b768635e8ba 100644 > --- a/drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c > +++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/ctrl.c > @@ -72,7 +72,7 @@ nvkm_control_mthd_pstate_attr(struct nvkm_control *ctrl, void *data, u32 size) > } *args = data; > struct nvkm_clk *clk = ctrl->device->clk; > const struct nvkm_domain *domain; > - struct nvkm_pstate *pstate; > + struct nvkm_pstate *pstate = NULL, *iter; > struct nvkm_cstate *cstate; > int i = 0, j = -1; > u32 lo, hi; > @@ -103,11 +103,16 @@ nvkm_control_mthd_pstate_attr(struct nvkm_control *ctrl, void *data, u32 size) > return -EINVAL; > > if (args->v0.state != NVIF_CONTROL_PSTATE_ATTR_V0_STATE_CURRENT) { > - list_for_each_entry(pstate, &clk->states, head) { > - if (i++ == args->v0.state) > + list_for_each_entry(iter, &clk->states, head) { > + if (i++ == args->v0.state) { > + pstate = iter;Is iter and the assignment really necessary ? Unless I am missing something, list_for_each_entry() always assigns pos (pstate/iter), even if the list is empty. If nothing is found, pstate would be NULL at the end, so> break; > + } > } > > + if (!pstate) > + return -EINVAL; > +... just this check should do to cover both the "not found" and "list empty" cases. Thanks, Guenter> lo = pstate->base.domain[domain->name]; > hi = lo; > list_for_each_entry(cstate, &pstate->list, head) {
Xiaomeng Tong
2022-Mar-27 06:59 UTC
[Nouveau] [PATCH] device: fix missing check on list iterator
On Sat, 26 Mar 2022 22:38:05 -0700, Guenter Roeck <linux at roeck-us.net> wrote:> > @@ -103,11 +103,16 @@ nvkm_control_mthd_pstate_attr(struct nvkm_control *ctrl, void *data, u32 size) > > return -EINVAL; > > > > if (args->v0.state != NVIF_CONTROL_PSTATE_ATTR_V0_STATE_CURRENT) { > > - list_for_each_entry(pstate, &clk->states, head) { > > - if (i++ == args->v0.state) > > + list_for_each_entry(iter, &clk->states, head) { > > + if (i++ == args->v0.state) { > > + pstate = iter; > > Is iter and the assignment really necessary ? Unless I am missing something, > list_for_each_entry() always assigns pos (pstate/iter), even if the list is > empty. If nothing is found, pstate would be NULL at the end, sothe pstate will not be NULL at the end! so the assignment is necessary! #define list_for_each_entry(pos, head, member) \ for (pos = __container_of((head)->next, pos, member); \ &pos->member != (head); \ pos = __container_of(pos->member.next, pos, member)) -- Xiaomeng Tong