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 54CF54F3EAA; Wed, 30 Sep 2026 17:00:53 +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=1790787654; cv=none; b=AWTPwi1BfSWjo7rGIO0KxJtWNs01rIDlDHbAFRpPMzOB5QrQ+mnh649cnWFvTmyzi/F5Nsg3D/HeTzJdNYEONf6+o49ZgUkZHHOuYvVpHxiC4XE5ygBmHwoHNO022gGdE3CzeNyUpmxc9ouo5DRPHweGZtuhiU8TrcD3hDwhcrk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790787654; c=relaxed/simple; bh=1PtWQhbihPOiy7h7PHRkTKqQtG5ybNs9gZVFITNcDpQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=huKwGETqht/qyGwQL5aEWbcVr03xvOELnsMLf0WbwY4hGvoODixfyi5E5mI9aHMvBvLhOa9HR1S6MxTB0iVuULxPX7meVulzpOXMkvCBCv31NJKYY54k+qRxxqeAoSvE11gADCF1UlQEmD9OKatniC8fuCIAXZIMyChkgl0phB4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IVU3x5yL; 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="IVU3x5yL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B17851F000FF; Wed, 30 Sep 2026 17:00:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790787653; bh=j5uLh5xOjOyASZn8D6TQHtIVj1+c6GnRSFvq37DYeh0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IVU3x5yLFirqpEvgVGH1rnokt7hPWykuGJlOWyFR68qs9+Shtr9xR3FLGZTLCiBBE Nxy+O/jzGs3rVKf1DdoaeLJPmK8KrvggiPq9jJ26RCy9DSSCd0vBRBdGU+Tyrc26zv jdS1HeXvVH5wY9kVIFwDC4DzHzr6PEAsbu4gw6FE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Peiyang He , Dmitry Osipenko Subject: [PATCH 7.2 307/457] drm/virtio: fix NULL pointer dereference on fence allocation failure Date: Wed, 30 Sep 2026 17:26:52 +0200 Message-ID: <20260930152352.653812245@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152346.024115587@linuxfoundation.org> References: <20260930152346.024115587@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peiyang He commit 846b3c64fe3e77d9db20a7e3e62dbbb637c773e1 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/virtio/virtgpu_submit.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- 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 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);