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
commit b628510397b5cafa1f5d3e848a28affd1c635302 upstream.
Commit 2e4955167ec5 ("firmware: qcom: scm: Fix __scm and waitq completion variable initialization") introduced a write barrier in probe function to store global '__scm' variable. We all known barriers are paired (see memory-barriers.txt: "Note that write barriers should normally be paired with read or address-dependency barriers"), therefore accessing it from concurrent contexts requires read barrier. Previous commit added such barrier in qcom_scm_is_available(), so let's use that directly.
Lack of this read barrier can result in fetching stale '__scm' variable value, NULL, and dereferencing it.
Note that barrier in qcom_scm_is_available() satisfies here the control dependency.
Fixes: ca61d6836e6f ("firmware: qcom: scm: fix a NULL-pointer dereference") Fixes: 449d0d84bcd8 ("firmware: qcom: scm: smc: switch to using the SCM allocator") Cc: stable@vger.kernel.org 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: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/firmware/qcom/qcom_scm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c index cde60566c793..4a1c05a7bf20 100644 --- a/drivers/firmware/qcom/qcom_scm.c +++ b/drivers/firmware/qcom/qcom_scm.c @@ -217,7 +217,10 @@ static DEFINE_SPINLOCK(scm_query_lock);
struct qcom_tzmem_pool *qcom_scm_get_tzmem_pool(void) { - return __scm ? __scm->mempool : NULL; + if (!qcom_scm_is_available()) + return NULL; + + return __scm->mempool; }
static enum qcom_scm_convention __get_convention(void)