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{ "id": 2220771, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2220771/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260408020030.247607-1-acelan.kao@canonical.com/", "project": { "id": 15, "url": "http://patchwork.ozlabs.org/api/1.1/projects/15/?format=api", "name": "Ubuntu Kernel", "link_name": "ubuntu-kernel", "list_id": "kernel-team.lists.ubuntu.com", "list_email": "kernel-team@lists.ubuntu.com", "web_url": null, "scm_url": null, "webscm_url": null }, "msgid": "<20260408020030.247607-1-acelan.kao@canonical.com>", "date": "2026-04-08T02:00:28", "name": "[SRU,N,0/2] BUG: kernel NULL pointer dereference in amdgpu", "submitter": { "id": 2976, "url": "http://patchwork.ozlabs.org/api/1.1/people/2976/?format=api", "name": "AceLan Kao", "email": "acelan.kao@canonical.com" }, "mbox": "http://patchwork.ozlabs.org/project/ubuntu-kernel/cover/20260408020030.247607-1-acelan.kao@canonical.com/mbox/", "series": [ { "id": 499057, "url": "http://patchwork.ozlabs.org/api/1.1/series/499057/?format=api", "web_url": "http://patchwork.ozlabs.org/project/ubuntu-kernel/list/?series=499057", "date": "2026-04-08T02:00:29", "name": "BUG: kernel NULL pointer dereference in amdgpu", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/499057/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2220771/comments/", "headers": { "Return-Path": "<kernel-team-bounces@lists.ubuntu.com>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=a2tUQ3tx;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com\n (client-ip=185.125.189.65; helo=lists.ubuntu.com;\n envelope-from=kernel-team-bounces@lists.ubuntu.com;\n receiver=patchwork.ozlabs.org)" ], "Received": [ "from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65])\n\t(using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits))\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fr5rN1Y2Mz1yDG\n\tfor <incoming@patchwork.ozlabs.org>; Wed, 08 Apr 2026 12:00:51 +1000 (AEST)", "from localhost ([127.0.0.1] helo=lists.ubuntu.com)\n\tby lists.ubuntu.com with esmtp (Exim 4.86_2)\n\t(envelope-from <kernel-team-bounces@lists.ubuntu.com>)\n\tid 1wAIDf-0005nr-1g; Wed, 08 Apr 2026 02:00:39 +0000", "from mail-qt1-f178.google.com ([209.85.160.178])\n by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.86_2) (envelope-from <acelan@gmail.com>) id 1wAIDc-0005ml-Nl\n for kernel-team@lists.ubuntu.com; Wed, 08 Apr 2026 02:00:36 +0000", "by mail-qt1-f178.google.com with SMTP id\n d75a77b69052e-50d6b9bca48so73171501cf.2\n for <kernel-team@lists.ubuntu.com>; Tue, 07 Apr 2026 19:00:36 -0700 (PDT)", "from localhost (211-75-139-220.hinet-ip.hinet.net. [211.75.139.220])\n by smtp.gmail.com with ESMTPSA id\n d75a77b69052e-50d4b32b59csm184452761cf.13.2026.04.07.19.00.32\n for <kernel-team@lists.ubuntu.com>\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Tue, 07 Apr 2026 19:00:33 -0700 (PDT)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=gmail.com; s=20251104; t=1775613635; x=1776218435; darn=lists.ubuntu.com;\n h=content-transfer-encoding:mime-version:message-id:date:subject:to\n :from:sender:from:to:cc:subject:date:message-id:reply-to;\n bh=Q1MpwvxmoPaSw7wZDuWa/T8gSG/hC1pD83lbneZO6MY=;\n b=a2tUQ3txflpsbeiKIa08SmXho1MDsF03HX5rBlt191o9eLQyGiWJhWbUU9c3mVF9rR\n tQWfoaezrS401WabHb7etT+v+q0Dw2xskZmLqtOdHUFtDa0T7co3b2E+nPnAmvWe8xwk\n Hny+mrs9UDShUuf4bmOWhXmAo8sN4jfQ1vGu0sj6SRxMCJH8LLH1S8eKb91LHK2xzjsG\n 5BxGYAQw9zcVvMemBH7BZ8K9vH3HPx1cN7tlI6ZpLqBCblEiVm79PazGTg7XO133rVV/\n ZQWW+zAM9+PG+AHiA55G40gu2lms7pulKOI6itG6yvf9gYA4lD9hVNH99T8ynPib6DP7\n ZGyA==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1775613635; x=1776218435;\n h=content-transfer-encoding:mime-version:message-id:date:subject:to\n :from:sender:x-gm-gg:x-gm-message-state:from:to:cc:subject:date\n :message-id:reply-to;\n bh=Q1MpwvxmoPaSw7wZDuWa/T8gSG/hC1pD83lbneZO6MY=;\n b=CaGm+LkF/sETPAnY5UQCjXoBJuWLESPEfEv1Rxn3pMhX+2Q2ICsSfHJnxJEMvu1Fel\n XdBSbUAkyIzvOvs7CQjOpJr3VNNKqzAeB54GY/S5m7egvLg1no0R3xVgv6njkG44URs/\n ZqW79plZhX+XcsGZDLpXx0wd2DC7kRvEXw5SyAB8RhEpWeUrCiEyn8PewBLtHOPNOMdj\n vlu95OShxV9LgsV6lt9DqNPADFdfiQcAV28VuG52XMGvwqSNoQDH0Lxwc/kGFIdRvYW+\n Yd4q8bDWd+DMGjN6vgcUqTHr/XtpKCpk9VGCY4afBi3CXRQDUNVSj/CNoL8rzucbcr2m\n heRw==", "X-Gm-Message-State": "AOJu0YwX0ku8uec2gmg1MC1BMTuMhHcrhxmpYOO1eOt9QbuHNDD/0aJb\n X+m8VQd0+tuLPKzofOgUI5PBgZRo53gLmXmhlKGX7GuMe7de1unfcHodEJBHRRyU", "X-Gm-Gg": "AeBDieuCuTkJDXNIHCTqZaLb0VA4xkAbKsnJcbtbWYuYaihNo9VMyJR6mW/sEVL2yvW\n /6/WiW9xnOFUWjq6PGT8B5EyrUf6okikePQ5txhEF4P74PZ/v47LTlraa6Di2HL1zJmlDi8BWWW\n csvVRrp5+XFbVZ/3+RpRFa6DcrxqyYy4htk9mAXGulI6/0tsQDJh8EYzECSZk1E3V0gHcURURSe\n oZCLIv/QTvXkzlr/+OilsJX3AL9Q3lM3wl4RbG+i3hKzbejjis50QBXwPa+4ovO7vxRjgjaK+Xo\n f9OcsDWpJ3VX4ktySVqqwnJQl8zEOH1A9SFmzsZ8tV59IlzDyQVp0jVtXcA0+VlZMN05LmaL2U7\n tbyAu0xhy+zfNlsY5qvcqxkrZ7Op0HSVKqdMxcLKGE7q5mWrAipCDAldf9ZzevF0ma+OM21dbUn\n msx8LZMsM8wWJvpgYGj3IWdCFjQi5rB9wg1058qOMBEP0w+CtHE2OixaKk+mkozrg=", "X-Received": "by 2002:a05:622a:1e8a:b0:50d:aa29:2b67 with SMTP id\n d75a77b69052e-50daa293e87mr55502391cf.49.1775613634364;\n Tue, 07 Apr 2026 19:00:34 -0700 (PDT)", "From": "AceLan Kao <acelan.kao@canonical.com>", "To": "kernel-team@lists.ubuntu.com", "Subject": "[SRU][N][PATCH 0/2] BUG: kernel NULL pointer dereference in amdgpu", "Date": "Wed, 8 Apr 2026 10:00:28 +0800", "Message-ID": "<20260408020030.247607-1-acelan.kao@canonical.com>", "X-Mailer": "git-send-email 2.53.0", "MIME-Version": "1.0", "Received-SPF": "pass client-ip=209.85.160.178; envelope-from=acelan@gmail.com;\n helo=mail-qt1-f178.google.com", "X-BeenThere": "kernel-team@lists.ubuntu.com", "X-Mailman-Version": "2.1.20", "Precedence": "list", "List-Id": "Kernel team discussions <kernel-team.lists.ubuntu.com>", "List-Unsubscribe": "<https://lists.ubuntu.com/mailman/options/kernel-team>,\n <mailto:kernel-team-request@lists.ubuntu.com?subject=unsubscribe>", "List-Archive": "<https://lists.ubuntu.com/archives/kernel-team>", "List-Post": "<mailto:kernel-team@lists.ubuntu.com>", "List-Help": "<mailto:kernel-team-request@lists.ubuntu.com?subject=help>", "List-Subscribe": "<https://lists.ubuntu.com/mailman/listinfo/kernel-team>,\n <mailto:kernel-team-request@lists.ubuntu.com?subject=subscribe>", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "base64", "Errors-To": "kernel-team-bounces@lists.ubuntu.com", "Sender": "\"kernel-team\" <kernel-team-bounces@lists.ubuntu.com>" }, "content": "From: \"Chia-Lin Kao (AceLan)\" <acelan.kao@canonical.com>\n\nBugLink: https://bugs.launchpad.net/bugs/2144577\n\n[Impact]\nSystem freezes during boot on machines with AMD Southern Islands (SI) GPUs\nusing the amdgpu driver\n.\nThe amdgpu driver calls flush_gpu_tlb_pasid() in a workqueue, but on SI\nhardware this function pointer is NULL. The kernel hits a NULL pointer\ndereference in amdgpu_gmc_flush_gpu_tlb_pasid() and crashes.\n\nError log:\nkernel: BUG: kernel NULL pointer dereference, address: 0000000000000000\nkernel: Workqueue: events amdgpu_tlb_fence_work [amdgpu]\nkernel: RIP: 0010:0x0\nkernel: Call Trace:\nkernel: amdgpu_gmc_flush_gpu_tlb_pasid+0xfd/0x480 [amdgpu]\nkernel: amdgpu_tlb_fence_work+0x77/0x110 [amdgpu]\n\nHits every boot on affected hardware. Regression from 6.17.0-14 to 6.17.0-19.\n\n[Fix]\nTwo patches fix this together:\n1. f4db9913e4d3 (\"drm/amdgpu: validate the flush_gpu_tlb_pasid()\")\n Adds a NULL check for flush_gpu_tlb_pasid before calling it.\n Upstream in v7.0-rc1.\n2. e3a6eff92bbd (\"drm/amdgpu: Fix validating flush_gpu_tlb_pasid()\")\n Fixes the first patch — the early return skipped the unlock, causing\n a deadlock. Changes the bare return to a goto that unlocks first.\n Upstream in v7.0-rc1.\n Fixes: f4db9913e4d3\n\n[Test Plan]\nOn a machine with an AMD SI GPU (Tahiti, Pitcairn, Verde, Oland, Hainan)\nbooted with amdgpu.si_support=1:\n\n$ sudo reboot\n\nWithout patches: kernel NULL pointer dereference during boot, system freezes.\nWith patches: system boots normally, no crash or error in dmesg.\n\nCheck dmesg after boot:\n$ dmesg | grep -i \"BUG\\|NULL pointer\\|amdgpu\"\n\nWithout patches: \"BUG: kernel NULL pointer dereference\" present.\nWith patches: no BUG or NULL pointer lines.\n\n[Where problems could occur]\nCould break TLB flushing on amdgpu.\n\nIf the NULL check gates too broadly, TLB flushes could be skipped on GPUs\nthat do have flush_gpu_tlb_pasid. This would cause stale TLB entries and\nGPU page faults or rendering corruption.\n\nThe unlock path change in the second patch touches the reset/lock logic in\namdgpu_gmc_flush_gpu_tlb_pasid(). A wrong goto target could leave the\nreset domain lock held, deadlocking the GPU.\n\n[Other Info]\nBoth patches are upstream in v7.0-rc1.\n\nPrike Liang (1):\n drm/amdgpu: validate the flush_gpu_tlb_pasid()\n\nTimur Kristóf (1):\n drm/amdgpu: Fix validating flush_gpu_tlb_pasid()\n\n drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 6 ++++++\n 1 file changed, 6 insertions(+)" }