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[82.37.195.13]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43569921da2sm4927533f8f.1.2026.01.16.04.10.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Jan 2026 04:10:04 -0800 (PST) From: Daniel Thompson Date: Fri, 16 Jan 2026 12:09:37 +0000 Subject: [PATCH] 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: <20260116-iommu-io_page_fault_null_fix-v1-1-6c20c2e62987@riscstar.com> X-B4-Tracking: v=1; b=H4sIAIAqamkC/x2MWwqAIBAArxL7nZD2ILpKhFittWAWmhFEd2/pZ 2DmYx6IGAgjdNkDAS+KtHsWmWcwrcYvKGhmB1WoppCyEbRvW2LqwyyorUnu1D45py3dwrZyrLA d60qVwIsjIOd/3w/v+wHzBVHIbgAAAA== 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=1396; i=daniel@riscstar.com; h=from:subject:message-id; bh=wzqwRBKyLSM4GRh0kCYODc/MRx83ikN2FZc7umGbfq8=; b=owEBbQKS/ZANAwAKAXzjJV0594ihAcsmYgBpaiqObiokix9ae2QyYoXTSoETuIWNZIj3AJUUG dcO25z3zdCJAjMEAAEKAB0WIQQvNUFTUPeVarpwrPB84yVdOfeIoQUCaWoqjgAKCRB84yVdOfeI oWobD/sGxlA1+2P2xosSrO13NYJuNZAvTUSac9q9A0JGt+RfbDnbjNkUz/OKwmpHoGl+ylFcOE4 xHMYQEmtqKF1KkXzkOPGr0IEN/KdKhvka+YTz+Uz1MhWM5GX2ayo865KyFqCrYXoexOiNDG/FE3 lSZcRReKaQ7mwbD5WfIiBtLJMIG7nPZv3TnBJUVnZvPOBGp8/4kERiYfaudH0y/EX8NuQEfXnJ6 6QvFoGHo9UUK7SLHbfjjA1UwECfGVHvMG6J3fj14t9rbSaQJNn23qhj6MqnP9RPshash32ysBFB NizeW7gcbGu0kHH6XW8dzfoJIa78Ue4O2Rmt4SAvCEB+qZl71K6+lb8b5qWv/c+tW76HFSHZRQo sNmT/9n2Qo6VIvTQ5lbSNZYemcwknir239IP8uf4PTBf/7pK8HhAbUa6uca/paZvJstYMLzZS4f Pf0Q79d+7ymhZvM5xgo7xB/KI8nk/x9ynnfRED6nl/S/yOY92z8RpnH7Kj5AmdZamfX9jJsAaWE aEJ10qFthfAZ6gcBLeZ14fK/lMIWA9iUv/GViESqtmXmzNcLgajTildIRTwsV7KMLwtqC84W762 IvCXiwv48f6E99w/KL8qF2IeUV9/moPd0y4Mh4DQyE8oR/eWC/VzoTQggoMKgSdiXXXBGsqMmID TURsYXBqfWJlzzQ== 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. Signed-off-by: Daniel Thompson --- 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