From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E0293E763B for ; Tue, 29 Sep 2026 08:26:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790670371; cv=none; b=GosTdERKd4otM+CeI/KYy5+JN2Ob+AZrC8oVAf6lbnJdrbgPz7ulo4G+ilUZClloJ7E/mXQHLFk0eaCvHSAuX7B+LaOOjkg2mB4Pfag9jquZ+KwIrlFIdrvUH+S7Q2V+gh73caLOdlKk0bAqucTTlmubRyCh7ZOJG/MYL3WOJhU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790670371; c=relaxed/simple; bh=N03ZQKU5Os7P4r6XIcHWh4hxOBqL36GD24Hr4Frzn94=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=LmJqvfiUHhuY6AwPjwm5hG73/qguniRmDD6aQKzbolM+hLPh2qWBkwrm7MbQsxHifOD29J1QJgSAzSBEFFUrfbOGrHvqjbIxk2G/sv8x0cCjvoK55QhbRLb99dzSnO/w1FBZdhLkGXgh+0mlap8kOKWJUS2WpallmD+laEn2la0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=MHNL8x0J; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="MHNL8x0J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77DE91F00893; Tue, 29 Sep 2026 08:26:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790670370; bh=Vx2nk2YqO5otqgYtcmVSHo4rew9gC9yzzh3C4nWRh+4=; h=Subject:To:Cc:From:Date; b=MHNL8x0JaMu/ePtvCXlz0PjTw2R1m3bJ5ccYV2/kH7XwRpivuIyByEGJx0sjRkJfm pkmyaSdcyqJVNBJNZ9Kp5y71WLthuVEmdjHz3UzMlnijm92dq/dhPFoVeXjSU5Q0tj kAnoyzYk4JDR1tl+L26k21VX45Yzq4bjklJMs0k8= Subject: FAILED: patch "[PATCH] drm/virtio: fix NULL pointer dereference on fence allocation" failed to apply to 6.1-stable tree To: peiyang_he@smail.nju.edu.cn,dmitry.osipenko@collabora.com Cc: From: Date: Tue, 29 Sep 2026 10:26:04 +0200 Message-ID: <2026092904-roundness-islamic-e935@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 846b3c64fe3e77d9db20a7e3e62dbbb637c773e1 # git commit -s git send-email --to '' --in-reply-to '2026092904-roundness-islamic-e935@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 846b3c64fe3e77d9db20a7e3e62dbbb637c773e1 Mon Sep 17 00:00:00 2001 From: Peiyang He Date: Wed, 9 Sep 2026 17:11:14 +0800 Subject: [PATCH] drm/virtio: fix NULL pointer dereference on fence allocation failure virtio_gpu_fence_alloc() can fail due to memory pressure and return NULL, but its caller like virtio_gpu_init_submit() never checks it. Later, virtio_gpu_init_submit() passes the NULL fence to virtio_gpu_fence_event_create(), which unconditionally dereferences it. Found when fuzzing the virtio driver with Syzkaller: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097] CPU: 1 UID: 0 PID: 9991 Comm: syz.0.121 Not tainted 7.2.0 #4 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline] RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline] RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505 Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00 RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216 RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090 RBP: 0000000000000000 R0virtio_gpu_virgl_process_cmd: ctrl 0x102, error 0x1203 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000 R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b FS: 00007fab480b96c0(0000) GS:ffff8880eb6e9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007effbf5e55a8 CR3: 0000000048d19000 CR4: 0000000000350ef0 Call Trace: drm_ioctl_kernel+0x1f4/0x3e0 drivers/gpu/drm/drm_ioctl.c:817 drm_ioctl+0x5f4/0xc70 drivers/gpu/drm/drm_ioctl.c:914 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fab471a82bd Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fab480b9018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fab47435fa0 RCX: 00007fab471a82bd RDX: 00002000000000c0 RSI: 00000000c0406442 RDI: 0000000000000003 RBP: 00007fab480b9080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fab47436038 R14: 00007fab47435fa0 R15: 00007ffe85ab0740 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline] RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline] RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505 Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00 RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216 RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000 R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b FS: 00007fab480b96c0(0000) GS:ffff888098ae9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f24c3759000 CR3: 0000000048d19000 CR4: 0000000000350ef0 ---------------- Code disassembly (best guess): 0: 85 ed test %ebp,%ebp 2: 0f 85 21 09 00 00 jne 0x929 8: e8 05 5a c9 fb call 0xfbc95a12 d: 48 8b 44 24 10 mov 0x10(%rsp),%rax 12: 48 8d b8 90 00 00 00 lea 0x90(%rax),%rdi 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2e: 0f 85 9a 0d 00 00 jne 0xdce 34: 48 8b 44 24 10 mov 0x10(%rsp),%rax 39: 4c 89 b0 90 00 00 00 mov %r14,0x90(%rax) Fix by checking virtio_gpu_fence_alloc() in virtio_gpu_init_submit() and returning -ENOMEM before any later code can dereference the NULL fence. Fixes: 70d1ace56db6 ("drm/virtio: Conditionally allocate virtio_gpu_fence") Cc: stable@vger.kernel.org Signed-off-by: Peiyang He Assisted-by: Codex:gpt-5.5 Signed-off-by: Dmitry Osipenko Link: https://patch.msgid.link/00EFE4BA92889B14+20260909091114.2622550-1-peiyang_he@smail.nju.edu.cn diff --git a/drivers/gpu/drm/virtio/virtgpu_submit.c b/drivers/gpu/drm/virtio/virtgpu_submit.c index 734b1e976a75..3d35326dd904 100644 --- a/drivers/gpu/drm/virtio/virtgpu_submit.c +++ b/drivers/gpu/drm/virtio/virtgpu_submit.c @@ -389,10 +389,13 @@ static int virtio_gpu_init_submit(struct virtio_gpu_submit *submit, if ((exbuf->flags & VIRTGPU_EXECBUF_FENCE_FD_OUT) || exbuf->num_out_syncobjs || exbuf->num_bo_handles || - drm_fence_event) + drm_fence_event) { out_fence = virtio_gpu_fence_alloc(vgdev, fence_ctx, ring_idx); - else + if (!out_fence) + return -ENOMEM; + } else { out_fence = NULL; + } if (drm_fence_event) { err = virtio_gpu_fence_event_create(dev, file, out_fence, ring_idx);