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[82.37.195.13]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4806e2bd243sm2394135e9.11.2026.01.28.07.48.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Jan 2026 07:48:25 -0800 (PST) From: Daniel Thompson Date: Wed, 28 Jan 2026 15:48:01 +0000 Subject: [PATCH v2] iommu: Fix NULL pointer deref when io_page_fault tracepoint fires Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260128-iommu-io_page_fault_null_fix-v2-1-de047be6dd3a@riscstar.com> X-B4-Tracking: v=1; b=H4sIALAvemkC/42NQQ6CMBBFr0JmbQ0dsSIr72FIU+oAkwAlLRAN6 d2tnMDNT95bvL9DIM8UoMp28LRxYDclwFMGtjdTR4JfiQFzVLmUSrAbxzWtnk1HujXrsOhpHQb d8lu0pWwKKptrgRdIidlT0kf+WSfuOSzOf463Tf7sn+FNCimUxdwiKbyXt4fnYMNi/Nm6EeoY4 xdRcdl9ywAAAA== X-Change-ID: 20260116-iommu-io_page_fault_null_fix-f81b4e8b5423 To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Will Deacon , Robin Murphy , linux-arm-kernel@lists.infradead.org, Daniel Thompson X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=1758; i=daniel@riscstar.com; h=from:subject:message-id; bh=CA4ugjQ1IEjW+6kqAc+hYZuO43p3F42A6CJda++BPeU=; b=owEBbQKS/ZANAwAKAXzjJV0594ihAcsmYgBpei+7xn8ZZiBl8xCqnIgD+Ld8t+5lgqTfxVf8h b0Z17Jume6JAjMEAAEKAB0WIQQvNUFTUPeVarpwrPB84yVdOfeIoQUCaXovuwAKCRB84yVdOfeI oUZND/9RY6F29ijnSmDBq/dwsNlREV122MJyeYlx4yZcygd8sC8B9fW7nagoG+zm9asqd6Q/ziS Qbqy8zqxoSs7BdtyvqAfKJkfGw5eyGxI9XTwVUqB/yskBEM2JsNzWrNID9Wm3DK0ciLG9mSwiyO EJu1ql1Fnfc/oPvMFs/xIvweP1qM2RT0ka5n58k9tSBdrkMcc7AtURdHuMzAjMqRJQEgDAp3gB2 0In2j5f3rmL6xSCcsnpMzKdfbO7hAhQREgqhVVhZZh6evXyCIjySls7oKz4Z/bFqgsahNWHJn2i qZY2ck6xR/AssS7XW9MgR622bTQukQwqRhBcuVTkf47jGUr2Jygbh5uBs1l+JnjQRi+mU2gJ3L0 TNO6/iym13M0gYr/4lsOKlfGWHI+2UWnvN2+ZHJdnbzZ9eRN1c55JjWm7d3NoM1wC4kFQGKNfau lFoKbRRWK9V19X2k5nSH0wWBMHC+YL5dX8nTN6LDprE6bRQO0dsT/G1aI4RX0te4gA+6Uw1je2z 6RBWq6/GTYwms8r/AmRNf8BYnf5CT/rJlD9zlT6J39JyKVilRh5CbaCGDJSv1lTwPluB7mZABlJ a7zaK5FMnNesIsc7YwPA/LndTRCDl5A/Ads59baINuKBjxYB6aOJexklSQmdAG/FZ+gPB5t7pC+ jD/6TD1uwuuG7uw== X-Developer-Key: i=daniel@riscstar.com; a=openpgp; fpr=E38BE19861669213F6E2661AA8A4E3BC5B7B28BE The arm-smmu driver is unable to allocate the blame for a page fault to a specific device so it calls report_iommu_fault() with the dev argument set to NULL. Normally this doesn't cause anything catastrophic but on a system with the io_page_fault tracepoint enabled this results in a NULL pointer deref (resulting in a fairly spectacular crash on the hardware I'm currently working on). Fix this by adding logic to the tracepoint to safely propagate NULL. Fixes: f8f934c180f6 ("iommu/arm-smmu: Add support for driver IOMMU fault ha= ndlers") Signed-off-by: Daniel Thompson Reviewed-by: Steven Rostedt (Google) --- Changes in v2: - Add a Fixes:. It points to the earliest point I can find where it becomes possible for the tracepoint to be triggered with dev set to NULL. - Link to v1: https://lore.kernel.org/r/20260116-iommu-io_page_fault_null_f= ix-v1-1-6c20c2e62987@riscstar.com --- include/trace/events/iommu.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/trace/events/iommu.h b/include/trace/events/iommu.h index 373007e567cb827458a729b8200bbcc1b7d76912..1315193f13b8812ad4e29e6b0c0= c66ca806ce08d 100644 --- a/include/trace/events/iommu.h +++ b/include/trace/events/iommu.h @@ -131,8 +131,8 @@ DECLARE_EVENT_CLASS(iommu_error, TP_ARGS(dev, iova, flags), =20 TP_STRUCT__entry( - __string(device, dev_name(dev)) - __string(driver, dev_driver_string(dev)) + __string(device, dev ? dev_name(dev) : NULL) + __string(driver, dev ? dev_driver_string(dev) : NULL) __field(u64, iova) __field(int, flags) ), --- base-commit: 0f61b1860cc3f52aef9036d7235ed1f017632193 change-id: 20260116-iommu-io_page_fault_null_fix-f81b4e8b5423 Best regards, --=20 Daniel Thompson