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drm/nouveau/clk: Fix an incorrect NULL check on list iterator

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The bug is here:
	if (nvkm_cstate_valid(clk, cstate, max_volt, clk->temp))
		return cstate;

The list iterator value 'cstate' will *always* be set and non-NULL
by list_for_each_entry_from_reverse(), so it is incorrect to assume
that the iterator value will be unchanged if the list is empty or no
element is found (In fact, it will be a bogus pointer to an invalid
structure object containing the HEAD). Also it missed a NULL check
at callsite and may lead to invalid memory access after that.

To fix this bug, just return 'encoder' when found, otherwise return
NULL. And add the NULL check.

Cc: stable@vger.kernel.org
Fixes: 1f7f3d91ad ("drm/nouveau/clk: Respect voltage limits in nvkm_cstate_prog")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220327075824.11806-1-xiam0nd.tong@gmail.com
This commit is contained in:
Xiaomeng Tong 2022-03-27 15:58:24 +08:00 committed by Lyude Paul
parent 36fe4f24ff
commit 1c3b2a27de
1 changed files with 4 additions and 2 deletions
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6
drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c
View file

@ -135,10 +135,10 @@ nvkm_cstate_find_best(struct nvkm_clk *clk, struct nvkm_pstate *pstate,
list_for_each_entry_from_reverse(cstate, &pstate->list, head) {
if (nvkm_cstate_valid(clk, cstate, max_volt, clk->temp))
break;
return cstate;
}
return cstate;
return NULL;
}
static struct nvkm_cstate *
@ -169,6 +169,8 @@ nvkm_cstate_prog(struct nvkm_clk *clk, struct nvkm_pstate *pstate, int cstatei)
if (!list_empty(&pstate->list)) {
cstate = nvkm_cstate_get(clk, pstate, cstatei);
cstate = nvkm_cstate_find_best(clk, pstate, cstate);
if (!cstate)
return -EINVAL;
} else {
cstate = &pstate->base;
}