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

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commit 1c3b2a27de upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiaomeng Tong 2022-03-27 15:58:24 +08:00 committed by Greg Kroah-Hartman
parent 461c0fdf94
commit 512027f8e2
1 changed files with 4 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

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;
}