linux-kernel - [PATCH v2 0/4] firmware: qcom: scm: fix potential race condition with tzmem

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Message-Id: <20250630-qcom-scm-race-v2-0-fa3851c98611@linaro.org>
Date: Mon, 30 Jun 2025 14:12:01 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, Johan Hovold <johan@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>, 
 Johan Hovold <johan+linaro@...nel.org>
Subject: [PATCH v2 0/4] firmware: qcom: scm: fix potential race condition
 with tzmem

There's a race condition between the SCM call API consumers and the TZMem
initialization in the SCM firmware driver. The internal __scm pointer is
assigned - marking SCM as ready for accepting calls - before the tzmem
memory pool is fully initialized. While the race is unlikely to be hit
thanks to the SCM driver being initialized early, it still must be
addressed.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
Changes in v2:
- add comments explaining the ordering of operations in probe()
- add Johan's Reported-by and Closes tags
- Link to v1: https://lore.kernel.org/r/20250625-qcom-scm-race-v1-0-45601e1f248b@linaro.org

---
Bartosz Golaszewski (4):
      firmware: qcom: scm: remove unused arguments from SHM bridge routines
      firmware: qcom: scm: take struct device as argument in SHM bridge enable
      firmware: qcom: scm: initialize tzmem before marking SCM as available
      firmware: qcom: scm: request the waitqueue irq *after* initializing SCM

 drivers/firmware/qcom/qcom_scm.c       | 95 ++++++++++++++++------------------
 drivers/firmware/qcom/qcom_scm.h       |  1 +
 drivers/firmware/qcom/qcom_tzmem.c     | 11 ++--
 include/linux/firmware/qcom/qcom_scm.h |  5 +-
 4 files changed, 55 insertions(+), 57 deletions(-)
---
base-commit: f817b6dd2b62d921a6cdc0a3ac599cd1851f343c
change-id: 20250624-qcom-scm-race-5e7737f7f39f

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@...aro.org>