From: Xiaomeng Tong xiam0nd.tong@gmail.com
stable inclusion from stable-v5.10.121 commit 97a9ec86ccb4e336ecde46db42b59b2ff7e0d719 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5L6CQ
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 1c3b2a27def609473ed13b1cd668cb10deab49b4 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: 1f7f3d91ad38a ("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... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c index dc184e857f85..5214fd0658b8 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/base.c @@ -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; }