From: Bjorn Andersson Date: Tue, 20 Aug 2024 22:59:34 +0000 (-0700) Subject: soc: qcom: pd-mapper: Fix singleton refcount X-Git-Tag: v6.11-rc6~9^2~4^2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c158ceb826068a8bbe3c9e78df420f47ba53c8a8;p=thirdparty%2Flinux.git soc: qcom: pd-mapper: Fix singleton refcount The Qualcomm pd-mapper is a refcounted singleton, but the refcount is never incremented, which means the as soon as any remoteproc instance stops the count will hit 0. At this point the pd-mapper QMI service is stopped, leaving firmware without access to the PD information. Stopping any other remoteproc instances will result in a use-after-free, which best case manifest itself as a refcount underflow: refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 354 at lib/refcount.c:87 refcount_dec_and_mutex_lock+0xc4/0x148 ... Call trace: refcount_dec_and_mutex_lock+0xc4/0x148 qcom_pdm_remove+0x40/0x118 [qcom_pd_mapper] ... Fix this by incrementing the refcount, so that the pd-mapper is only torn down when the last remoteproc stops, as intended. Fixes: 1ebcde047c54 ("soc: qcom: add pd-mapper implementation") Signed-off-by: Bjorn Andersson Reviewed-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20240820-pd-mapper-refcount-fix-v1-1-03ea65c0309b@quicinc.com Signed-off-by: Bjorn Andersson --- diff --git a/drivers/soc/qcom/qcom_pd_mapper.c b/drivers/soc/qcom/qcom_pd_mapper.c index 9afa09c3920e1..2228595a3dc5a 100644 --- a/drivers/soc/qcom/qcom_pd_mapper.c +++ b/drivers/soc/qcom/qcom_pd_mapper.c @@ -635,6 +635,8 @@ static int qcom_pdm_probe(struct auxiliary_device *auxdev, ret = PTR_ERR(data); else __qcom_pdm_data = data; + } else { + refcount_inc(&__qcom_pdm_data->refcnt); } auxiliary_set_drvdata(auxdev, __qcom_pdm_data);