6.12-stable review patch. If anyone has any objections, please let me know.
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From: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org
[ Upstream commit 1e76b546e6fca7eb568161f408133904ca6bcf4f ]
If SCM driver fails the probe, it should not leave global '__scm' variable assigned, because external users of this driver will assume the probe finished successfully. For example TZMEM parts ('__scm->mempool') are initialized later in the probe, but users of it (__scm_smc_call()) rely on the '__scm' variable.
This fixes theoretical NULL pointer exception, triggered via introducing probe deferral in SCM driver with call trace:
qcom_tzmem_alloc+0x70/0x1ac (P) qcom_tzmem_alloc+0x64/0x1ac (L) qcom_scm_assign_mem+0x78/0x194 qcom_rmtfs_mem_probe+0x2d4/0x38c platform_probe+0x68/0xc8
Fixes: 40289e35ca52 ("firmware: qcom: scm: enable the TZ mem allocator") Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org Link: https://lore.kernel.org/r/20241209-qcom-scm-missing-barriers-and-all-sort-of... Signed-off-by: Bjorn Andersson andersson@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/qcom/qcom_scm.c | 42 ++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c index 14afd68664a91..a6bdedbbf7088 100644 --- a/drivers/firmware/qcom/qcom_scm.c +++ b/drivers/firmware/qcom/qcom_scm.c @@ -2001,13 +2001,17 @@ static int qcom_scm_probe(struct platform_device *pdev)
irq = platform_get_irq_optional(pdev, 0); if (irq < 0) { - if (irq != -ENXIO) - return irq; + if (irq != -ENXIO) { + ret = irq; + goto err; + } } else { ret = devm_request_threaded_irq(__scm->dev, irq, NULL, qcom_scm_irq_handler, IRQF_ONESHOT, "qcom-scm", __scm); - if (ret < 0) - return dev_err_probe(scm->dev, ret, "Failed to request qcom-scm irq\n"); + if (ret < 0) { + dev_err_probe(scm->dev, ret, "Failed to request qcom-scm irq\n"); + goto err; + } }
__get_convention(); @@ -2026,14 +2030,18 @@ static int qcom_scm_probe(struct platform_device *pdev) qcom_scm_disable_sdi();
ret = of_reserved_mem_device_init(__scm->dev); - if (ret && ret != -ENODEV) - return dev_err_probe(__scm->dev, ret, - "Failed to setup the reserved memory region for TZ mem\n"); + if (ret && ret != -ENODEV) { + dev_err_probe(__scm->dev, ret, + "Failed to setup the reserved memory region for TZ mem\n"); + goto err; + }
ret = qcom_tzmem_enable(__scm->dev); - if (ret) - return dev_err_probe(__scm->dev, ret, - "Failed to enable the TrustZone memory allocator\n"); + if (ret) { + dev_err_probe(__scm->dev, ret, + "Failed to enable the TrustZone memory allocator\n"); + goto err; + }
memset(&pool_config, 0, sizeof(pool_config)); pool_config.initial_size = 0; @@ -2041,9 +2049,11 @@ static int qcom_scm_probe(struct platform_device *pdev) pool_config.max_size = SZ_256K;
__scm->mempool = devm_qcom_tzmem_pool_new(__scm->dev, &pool_config); - if (IS_ERR(__scm->mempool)) - return dev_err_probe(__scm->dev, PTR_ERR(__scm->mempool), - "Failed to create the SCM memory pool\n"); + if (IS_ERR(__scm->mempool)) { + dev_err_probe(__scm->dev, PTR_ERR(__scm->mempool), + "Failed to create the SCM memory pool\n"); + goto err; + }
/* * Initialize the QSEECOM interface. @@ -2059,6 +2069,12 @@ static int qcom_scm_probe(struct platform_device *pdev) WARN(ret < 0, "failed to initialize qseecom: %d\n", ret);
return 0; + +err: + /* Paired with smp_load_acquire() in qcom_scm_is_available(). */ + smp_store_release(&__scm, NULL); + + return ret; }
static void qcom_scm_shutdown(struct platform_device *pdev)