[{"id":3678166,"web_url":"http://patchwork.ozlabs.org/comment/3678166/","msgid":"","list_archive_url":null,"date":"2026-04-16T13:23:51","subject":"ACK: [SRU][N:linux-bluefield][PATCH v1 0/2] UBUNTU: SAUCE: vfio:\n Export vfio device get and put registration helpers","submitter":{"id":91694,"url":"http://patchwork.ozlabs.org/api/people/91694/","name":"Alessio Faina","email":"alessio.faina@canonical.com"},"content":"On Thu, Apr 16, 2026 at 03:14:04PM +0300, Stav Aviram wrote:\n> BugLink: https://bugs.launchpad.net/bugs/2148554\n> \n> SRU Justification:\n> \n> [IMPACT]\n> A kernel NULL pointer dereference occurs on Nvidia BlueField DPUs running Ubuntu 24.04\n> (Noble) with linux-bluefield-6.8. The crash is triggered when closing a dma_buf file\n> descriptor associated with a vfio_pci device. The root cause is that\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() call vfio_put_device() to\n> release a reference, but the reference was acquired with vfio_device_get(), which uses\n> a separate refcount (device->refcount). Using vfio_put_device() incorrectly decrements\n> the kobject refcount, triggering a refcount underflow and kernel crash.\n> \n> [FIX]\n> Two custom patches are submitted:\n> - UBUNTU: SAUCE: vfio: Export vfio device get and put registration helpers — exports\n> vfio_device_try_get_registration and vfio_device_put_registration via\n> EXPORT_SYMBOL_GPL in vfio_main.c and adds their declarations to vfio.h, making them\n> available to other VFIO modules.\n> - UBUNTU: SAUCE: vfio/pci: Use the correct ref count — fixes\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() to call\n> vfio_device_put_registration() instead of vfio_put_device(), correctly matching the\n> reference acquisition done via vfio_device_get().\n> \n> [TEST CASE]\n> Compile tested on linux-bluefield-6.8 on the master-next branch.\n> Functionally verified: the NULL pointer dereference no longer reproduces after applying\n> the fix.\n> \n> [Regression Potential]\n> Low. The change corrects an incorrect function call in the release path, and the fix\n> has been functionally verified on the affected setup.\n> \n> Amir Tzin (1):\n> UBUNTU: SAUCE: vfio/pci: Use the correct ref count\n> \n> Vivek Kasireddy (1):\n> UBUNTU: SAUCE: vfio: Export vfio device get and put registration\n> helpers\n> \n> drivers/vfio/pci/dma_buf.c | 4 ++--\n> drivers/vfio/vfio_main.c | 2 ++\n> include/linux/vfio.h | 2 ++\n> 3 files changed, 6 insertions(+), 2 deletions(-)\n> \n> -- \n> 2.38.1\n> \n> \n> -- \n> kernel-team mailing list\n> kernel-team@lists.ubuntu.com\n> https://lists.ubuntu.com/mailman/listinfo/kernel-team\n\nAcked-by: Alessio Faina ","headers":{"Return-Path":"","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\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=YE2JBhOM;\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 4fxJd25MtTz1yCv\n\tfor ; Thu, 16 Apr 2026 23:24:06 +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 )\n\tid 1wDMhH-0005KA-08; Thu, 16 Apr 2026 13:23:55 +0000","from smtp-relay-internal-0.internal ([10.131.114.225]\n helo=smtp-relay-internal-0.canonical.com)\n by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.86_2) (envelope-from )\n id 1wDMhG-0005K1-7f\n for kernel-team@lists.ubuntu.com; Thu, 16 Apr 2026 13:23:54 +0000","from mail-wm1-f71.google.com (mail-wm1-f71.google.com\n [209.85.128.71])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest\n SHA256)\n (No client certificate requested)\n by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 1CE473F7D2\n for ; Thu, 16 Apr 2026 13:23:54 +0000 (UTC)","by mail-wm1-f71.google.com with SMTP id\n 5b1f17b1804b1-488d9e1e61aso44190725e9.0\n for ; Thu, 16 Apr 2026 06:23:54 -0700 (PDT)","from localhost (93-35-126-76.ip55.fastwebnet.it. 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The crash is triggered when closing a dma_buf file\n> descriptor associated with a vfio_pci device. The root cause is that\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() call vfio_put_device() to\n> release a reference, but the reference was acquired with vfio_device_get(), which uses\n> a separate refcount (device->refcount). Using vfio_put_device() incorrectly decrements\n> the kobject refcount, triggering a refcount underflow and kernel crash.\n>\n> [FIX]\n> Two custom patches are submitted:\n> - UBUNTU: SAUCE: vfio: Export vfio device get and put registration helpers — exports\n> vfio_device_try_get_registration and vfio_device_put_registration via\n> EXPORT_SYMBOL_GPL in vfio_main.c and adds their declarations to vfio.h, making them\n> available to other VFIO modules.\n> - UBUNTU: SAUCE: vfio/pci: Use the correct ref count — fixes\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() to call\n> vfio_device_put_registration() instead of vfio_put_device(), correctly matching the\n> reference acquisition done via vfio_device_get().\n>\n> [TEST CASE]\n> Compile tested on linux-bluefield-6.8 on the master-next branch.\n> Functionally verified: the NULL pointer dereference no longer reproduces after applying\n> the fix.\n>\n> [Regression Potential]\n> Low. The change corrects an incorrect function call in the release path, and the fix\n> has been functionally verified on the affected setup.\n>\n> Amir Tzin (1):\n> UBUNTU: SAUCE: vfio/pci: Use the correct ref count\n>\n> Vivek Kasireddy (1):\n> UBUNTU: SAUCE: vfio: Export vfio device get and put registration\n> helpers\n>\n> drivers/vfio/pci/dma_buf.c | 4 ++--\n> drivers/vfio/vfio_main.c | 2 ++\n> include/linux/vfio.h | 2 ++\n> 3 files changed, 6 insertions(+), 2 deletions(-)\n>","headers":{"Return-Path":"","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\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=cCR4FmqA;\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 4fxK4D35Y9z1yHP\n\tfor ; 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boundary=\"===============2531091258610605204==\"","Errors-To":"kernel-team-bounces@lists.ubuntu.com","Sender":"\"kernel-team\" "}},{"id":3678521,"web_url":"http://patchwork.ozlabs.org/comment/3678521/","msgid":"","list_archive_url":null,"date":"2026-04-17T06:55:34","subject":"APPLIED: [SRU][N:linux-bluefield][PATCH v1 0/2] UBUNTU: SAUCE: vfio:\n Export vfio device get and put registration helpers","submitter":{"id":91694,"url":"http://patchwork.ozlabs.org/api/people/91694/","name":"Alessio Faina","email":"alessio.faina@canonical.com"},"content":"On Thu, Apr 16, 2026 at 03:14:04PM +0300, Stav Aviram wrote:\n> BugLink: https://bugs.launchpad.net/bugs/2148554\n> \n> SRU Justification:\n> \n> [IMPACT]\n> A kernel NULL pointer dereference occurs on Nvidia BlueField DPUs running Ubuntu 24.04\n> (Noble) with linux-bluefield-6.8. The crash is triggered when closing a dma_buf file\n> descriptor associated with a vfio_pci device. The root cause is that\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() call vfio_put_device() to\n> release a reference, but the reference was acquired with vfio_device_get(), which uses\n> a separate refcount (device->refcount). Using vfio_put_device() incorrectly decrements\n> the kobject refcount, triggering a refcount underflow and kernel crash.\n> \n> [FIX]\n> Two custom patches are submitted:\n> - UBUNTU: SAUCE: vfio: Export vfio device get and put registration helpers — exports\n> vfio_device_try_get_registration and vfio_device_put_registration via\n> EXPORT_SYMBOL_GPL in vfio_main.c and adds their declarations to vfio.h, making them\n> available to other VFIO modules.\n> - UBUNTU: SAUCE: vfio/pci: Use the correct ref count — fixes\n> vfio_pci_dma_buf_release() and vfio_pci_dma_buf_cleanup() to call\n> vfio_device_put_registration() instead of vfio_put_device(), correctly matching the\n> reference acquisition done via vfio_device_get().\n> \n> [TEST CASE]\n> Compile tested on linux-bluefield-6.8 on the master-next branch.\n> Functionally verified: the NULL pointer dereference no longer reproduces after applying\n> the fix.\n> \n> [Regression Potential]\n> Low. The change corrects an incorrect function call in the release path, and the fix\n> has been functionally verified on the affected setup.\n> \n> Amir Tzin (1):\n> UBUNTU: SAUCE: vfio/pci: Use the correct ref count\n> \n> Vivek Kasireddy (1):\n> UBUNTU: SAUCE: vfio: Export vfio device get and put registration\n> helpers\n> \n> drivers/vfio/pci/dma_buf.c | 4 ++--\n> drivers/vfio/vfio_main.c | 2 ++\n> include/linux/vfio.h | 2 ++\n> 3 files changed, 6 insertions(+), 2 deletions(-)\n> \n> -- \n> 2.38.1\n> \n> \n> -- \n> kernel-team mailing list\n> kernel-team@lists.ubuntu.com\n> https://lists.ubuntu.com/mailman/listinfo/kernel-team\n\nApplied to n:linux-bluefield \n\nThanks!\n- Alessio Faina","headers":{"Return-Path":"","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\" (4096-bit key;\n unprotected) header.d=canonical.com header.i=@canonical.com\n header.a=rsa-sha256 header.s=20251003 header.b=WClTJx2S;\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 4fxlyR1tmVz1yGt\n\tfor ; Fri, 17 Apr 2026 16:55:43 +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 )\n\tid 1wDd73-0005Tc-Mr; Fri, 17 Apr 2026 06:55:37 +0000","from smtp-relay-internal-1.internal ([10.131.114.114]\n helo=smtp-relay-internal-1.canonical.com)\n by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128)\n (Exim 4.86_2) (envelope-from )\n id 1wDd72-0005T4-W6\n for kernel-team@lists.ubuntu.com; Fri, 17 Apr 2026 06:55:37 +0000","from mail-wm1-f70.google.com (mail-wm1-f70.google.com\n [209.85.128.70])\n (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest\n SHA256)\n (No client certificate requested)\n by smtp-relay-internal-1.canonical.com (Postfix) with ESMTPS id D87693F620\n for ; Fri, 17 Apr 2026 06:55:36 +0000 (UTC)","by mail-wm1-f70.google.com with SMTP id\n 5b1f17b1804b1-488c0120047so1669645e9.0\n for ; Thu, 16 Apr 2026 23:55:36 -0700 (PDT)","from localhost (93-34-57-252.ip48.fastwebnet.it. 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