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: [email protected]
> Fixes: 9838366c1597d ("drm/nouveau/device: initial control object class, with pstate control methods")
> Signed-off-by: Xiaomeng Tong <[email protected]>
> ---
> 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) {
On Sat, 26 Mar 2022 22:38:05 -0700, Guenter Roeck <[email protected]> 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, so
the 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
On 3/26/22 23:59, Xiaomeng Tong wrote:
> On Sat, 26 Mar 2022 22:38:05 -0700, Guenter Roeck <[email protected]> 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, so
>
> the 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))
>
Uuh, yes, you are correct. Sorry for the noise.
Guenter