From nobody Mon Feb 9 15:00:03 2026 Received: from mail-pg1-f175.google.com (mail-pg1-f175.google.com [209.85.215.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B16AC45BE3 for ; Sun, 25 Jan 2026 14:33:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.175 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769351633; cv=none; b=UeMQpCJS5vGJLKb0uCMTYylA+J9VJ8eBwXgX6U/p3OeX6L1Ljr+ooZvImdMyjbITqJg6xDUXahwePaZbzgCErInMQGd6/0nIKk8gdM/9fCY1yLzKatXF0QeKp4bESyDhPlepERbzngI8NPpz3QL0QXoKcZKOWWSq85XKjQspIqM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769351633; c=relaxed/simple; bh=Q666l43IITdXRoaRDN9WaME4ByglguKOboN01FWMscU=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=XVB0WS1guk3HyQ2+PxxYkauvnt+8z7Dcy6jIZYvvAIKUeo0OALmNFgFa7RrX9RzlPzxlSqfCaZqXNaIkvaZV2ASCpe92s2qXVkmRhbEZWRXphFQgAlQJUCPFJcRqxLwuFnfgxlTZfEnM7TkMssCmdtYbMloaQ4oSzRcjIHJ+mco= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=DEMeSKG0; arc=none smtp.client-ip=209.85.215.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="DEMeSKG0" Received: by mail-pg1-f175.google.com with SMTP id 41be03b00d2f7-c5e051a47ddso2443053a12.1 for ; Sun, 25 Jan 2026 06:33:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769351632; x=1769956432; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=9vrpTgp19j2v2S0F0+kVV2ZQQrhahMGVY6XxldYPxCk=; b=DEMeSKG0WiRBHe5OXktvA0bc0Z1acAhoffx86wR5/iO/AILxT5q7ezpvr7h3Lyd5Es /r5pSX6DkIB699wuSXiJti5SjGZIQuPwYH0D+DE52J4ndtwsH5+12xf+xZEB3R3RGkJe 0TrvdvWFK2ICG43KlQgOC6oRYprKe7rPwZHzqOfAByCcC8loSWqXTrEf/RhlMLvyvcyU JDxgJ8rVTd8Jc95KzlEY8VxvoTamPqLdjN9XbgRvrZtY1ngSYxE7Zy6W3D3lNBB3+IwQ CdR28TSUCwlLwyScD6nQWTA3m5kOI/Lz/1yrLLzAf2A8FiLDdcaH3oO9Y7B3wbK5Zo+C spVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769351632; x=1769956432; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=9vrpTgp19j2v2S0F0+kVV2ZQQrhahMGVY6XxldYPxCk=; b=CiRmXcMlfcywsOkKs746IQxsRmsBiBkU/l0IQbJIvwNUJpdPfLFF3ZUgW7vsxERRsQ BTUU1gL3GI9alOBrz2PqrXfEncXWg6Nt+uipMPVtifIfc4laWhE0/Xt6OhhCBfmUCFZ5 7aVIM3H+7gQ0SmwDlnKI7Kh1XDfi8HQxZZEyy9PApCh1hiAfPqqEkZYiSANV2T0qzdw6 qrxTxB3VRCY1NNDVft8WOtWzhKDFe+GGrPUFlazCaT2g0Y1SokTjnt4BfMP7cDUxzBNL Y3ScBr6yqWgFbAUUfPhh1dtsitkUvdaq9e8gI5qa03QRVShXrTKYdYb/oc8TMW3PrmrM ftKg== X-Gm-Message-State: AOJu0YxOI/D5S78/u7WV8UwiClKX3R4+y7Av4Ys62EglrCmGMjVhsUro kjfm/Gavzcdz091Fj6rmFZ5cS3EXsoZzgFsDfF+CWxpGiVlJOGVk1bEhiRau/m/lunY= X-Gm-Gg: AZuq6aKrc+o+Tz/FQHtBxC/4+L0OpVY9IxiAvpFdxHwlETdUTjMrWZ6+E9XYTwPsHYF gFl2PfqEH4WnzWfTyUv46Xe6oBtSLK+tXjeIJPbulokh0xY2sUT4Lh8VamV6034MnL3LONde8S0 Kl1MoDJHVJRRVn/XbMiXqblESks0H/dtKywfMJTT15UyQegq5d8KfhZ/k36F2NzcE5N3LS6iHc5 jc/x53le+RzGd/vjjSM4OFtstqP1p/PY6FgUGtBrWzVo//Q4mYyujm65bmvIzm4XEvy9zAkKBbK PwzrKCcLhHoVcyUOACKZYVe8SAU994D/Mi05FZ00lqV0pcmnf/cT5F1fM4fuVQRhq0LsKeswQi4 oCpYaBhHXRo6H6XvU6Zz3ZB5b+3fjFCXTUFW8NDrkUu4RZxIdHDwQmFdenOZZjCSLb9+Ehf9fwe BOJoJlMENESnZyEPHT6IBOUXMZWiZlakuHSXSShJsJ8A6L8xwWY2Q= X-Received: by 2002:a17:90b:3d12:b0:340:b908:9665 with SMTP id 98e67ed59e1d1-353c418d276mr1450186a91.37.1769351631814; Sun, 25 Jan 2026 06:33:51 -0800 (PST) Received: from fric.. ([210.73.43.101]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-353354a6b06sm9351073a91.10.2026.01.25.06.33.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Jan 2026 06:33:51 -0800 (PST) From: Jiakai Xu X-Google-Original-From: Jiakai Xu To: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, kvm-riscv@lists.infradead.org, kvm@vger.kernel.org Cc: Alexandre Ghiti , Albert Ou , Palmer Dabbelt , Paul Walmsley , Atish Patra , Anup Patel , Jiakai Xu , Jiakai Xu Subject: [PATCH v4] RISC-V: KVM: Fix null pointer dereference in kvm_riscv_aia_imsic_has_attr() Date: Sun, 25 Jan 2026 14:33:44 +0000 Message-Id: <20260125143344.2515451-1-xujiakai2025@iscas.ac.cn> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add a null pointer check for imsic_state before dereferencing it in kvm_riscv_aia_imsic_has_attr(). While the function checks that the vcpu exists, it doesn't verify that the vcpu's imsic_state has been initialized, leading to a null pointer dereference when accessed. This issue was discovered during fuzzing of RISC-V KVM code. The crash occurs when userspace calls KVM_HAS_DEVICE_ATTR ioctl on an AIA IMSIC device before the IMSIC state has been fully initialized for a vcpu. The crash manifests as: Unable to handle kernel paging request at virtual address dfffffff00000001 ... epc : kvm_riscv_aia_imsic_has_attr+0x464/0x50e arch/riscv/kvm/aia_imsic.c:998 ... kvm_riscv_aia_imsic_has_attr+0x464/0x50e arch/riscv/kvm/aia_imsic.c:998 aia_has_attr+0x128/0x2bc arch/riscv/kvm/aia_device.c:471 kvm_device_ioctl_attr virt/kvm/kvm_main.c:4722 [inline] kvm_device_ioctl+0x296/0x374 virt/kvm/kvm_main.c:4739 ... The fix adds a check to return -ENODEV if imsic_state is NULL, which is consistent with other error handling in the function and prevents the null pointer dereference. Fixes: 5463091a51cf ("RISC-V: KVM: Expose IMSIC registers as attributes of = AIA irqchip") Signed-off-by: Jiakai Xu Signed-off-by: Jiakai Xu Reviewed-by: Anup Patel --- V3 -> V4: Fix typo in Signed-off-by email address. V2 -> V3: Moved isel assignment after imsic_state NULL check. Placed patch version history after '---' separator. Added parentheses to function name in subject. V1 -> V2: Added Fixes tag and drop external link as suggested. arch/riscv/kvm/aia_imsic.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c index e597e86491c3b..cd070d83663a9 100644 --- a/arch/riscv/kvm/aia_imsic.c +++ b/arch/riscv/kvm/aia_imsic.c @@ -993,8 +993,11 @@ int kvm_riscv_aia_imsic_has_attr(struct kvm *kvm, unsi= gned long type) if (!vcpu) return -ENODEV; =20 - isel =3D KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type); imsic =3D vcpu->arch.aia_context.imsic_state; + if (!imsic) + return -ENODEV; + + isel =3D KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type); return imsic_mrif_isel_check(imsic->nr_eix, isel); } =20 --=20 2.34.1