From nobody Mon Feb 9 12:14:10 2026 Received: from mail-pl1-f179.google.com (mail-pl1-f179.google.com [209.85.214.179]) (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 6F5252C0F75 for ; Tue, 27 Jan 2026 08:43:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769503434; cv=none; b=ZysJDeWSfKt1ZMjzMdlfeQs0syAUTFcmCSRl0pyIe0ISl+GFPD6p1MsbrZMlZDHfqhv8pLt03vX7H8vB5q9mh7i50FSqNXthFPcqe6uzqe4HKQXdGATubzO5bZvjkWSUZMtJDEagk0ZPtttc+NVrOT7Ec9vH1VQY0JS7fhb3xeU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769503434; c=relaxed/simple; bh=GzvtIUis0EMsZG1slqRGy7Qecih1MuOYCpwXvRC5QNM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=f9eOreDPPckCScrjOLb27y2uJc0C6KZM5XaHisxoSZbBVLXTmPvUCp4ncKlG6vxQHc3WeVMUux+d1VatJWESaSA5oNQKqhEm6Bz6/G8zKDAvK+gBT1yDI0tNCpauBs814AeL+k9u6mlo36EWyIs1XYvFJKzM9wP7G6IDNgjVU+I= 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=TukUBUep; arc=none smtp.client-ip=209.85.214.179 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="TukUBUep" Received: by mail-pl1-f179.google.com with SMTP id d9443c01a7336-2a7a9b8ed69so57613395ad.2 for ; Tue, 27 Jan 2026 00:43:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769503433; x=1770108233; 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=IsvMU6ygmVPOfBtUBm6r4nNfbsjDFVMoFcdeUelLuBA=; b=TukUBUepEsVFjYLDivSjQGkpGP/Tnuwng5lFE3V+tb4cXb8xncY7p6gZFifcjd/KQS 67Rspo3VTCNXSpaQyygiiInj72aKoK0YJzIYAZoeVfWrZTaYJumpWUYvR5FG8z9PNh82 JMolMqllU28hjrAIVuNdjpzVGXA26HPhSKk8bq2MlyMn7/TnxniLvUA3oRa3rJ9xvR7J Y/T7SxZqEm4wKkwAr6Ny0vEbyvwKsjiwXK2gVZOzN+BmN1rdA1tFuqVXmSm3RzSf68+B MIdgRheJX6PPu1dijjJYOJTTKtLserAEXZeh4Sr//Uy8xH8eGR5/JzJYxeuUu8JhfSh/ HmNw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769503433; x=1770108233; 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=IsvMU6ygmVPOfBtUBm6r4nNfbsjDFVMoFcdeUelLuBA=; b=ZraSE/pGOhiRTKmGhedikemnG6NW2pfsZ5gUMFmUHvEH+eIEp2jtaRqO0R3bqfDr9R 2+9Uswim92xmaRb2q8lxoXuD4YAmCYg2+M7caubc1QxxHmqSp83CZrwTwnL1iqurKBih iV+1lizgteTBLi55Cj6cFir7Tl/JlptXmZm+rsPdrYZMKxs18fmZIOnnvWtrzE5JXSj0 Wh3a4L31mTHJdswo9rJWfrj2WTfJ8R+5raGHMjbEU0cLo0jD/SzDbw1S4wdl0yDlO/ic oWDQ/CIxE05Wm3Oeu0kQYx+RxPLBJSqqJX2IYw0EdPVXmsHGXmdOU+wurgk3xc5dHYIM 1+ZA== X-Gm-Message-State: AOJu0YyW1+KOgFLSyG+hZCVQrjUPobRFIMIWfO7dH/DDLcmqv0qu44ns 2shshAUc1s7dmuI98wtuzZIVOu8zqREU3kQjwlTZ5ACxYw3Gcq/ySS/htYvo+xsh3lU= X-Gm-Gg: AZuq6aILlVTI46D1JQKhsaKrtuqqLk1ntbHU5iuBdYbzUmCrvbQflqlcGDjA4mfM6Fb prAEWhgctK4Wcp5M8hc8obZtJSI0JVG/XsKDZLEYzbGJYCmEVw/br3tkSDAkl6N7VE4Dm/a7bpc Uef35oWRWVNkk5+AOUdnmwaZv2EAyaaL9LHkrYfcnqADyC+/3VMzZ7/g/F+5h4scV1k4tlN6SZi b2Fe9LyQKrL/h4Zn46okF6SAsHHrvo72pal3zDIHW9HAKRWbZOscxtITx8PHvoDcLCbY1vZ5xD6 dIJUj3+yUqrfevzy9nvDNW4MCVRYphzBvRpDgP1Y0AToBE/79FZCPzQ2IezcxQd6K3YUxBE62YX Opeb8HJXfsP+bpYiJA76moVEUdXVcSljlvMkzooc+ZkjtuWTXXl0K+jzh3aKUxpElaRCb/6kHk4 TmKsNN2uaUCHsn5k69kiiEFBlln9Ws1MshKnj9KIHw X-Received: by 2002:a17:903:2c6:b0:24b:270e:56c7 with SMTP id d9443c01a7336-2a870d7a907mr11402265ad.7.1769503432479; Tue, 27 Jan 2026 00:43:52 -0800 (PST) Received: from fric.. ([210.73.43.101]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a802de5cf8sm108838235ad.42.2026.01.27.00.43.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jan 2026 00:43:52 -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: Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Jiakai Xu , Jiakai Xu Subject: [PATCH] RISC-V: KVM: Skip IMSIC update if vCPU IMSIC state is not initialized Date: Tue, 27 Jan 2026 08:43:13 +0000 Message-Id: <20260127084313.3496485-1-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" kvm_riscv_vcpu_aia_imsic_update() assumes that the vCPU IMSIC state has already been initialized and unconditionally accesses imsic->vsfile_lock. However, in fuzzed ioctl sequences, the AIA device may be initialized at the VM level while the per-vCPU IMSIC state is still NULL. This leads to invalid access when entering the vCPU run loop before IMSIC initialization has completed. The crash manifests as: Unable to handle kernel paging request at virtual address dfffffff00000006 ... kvm_riscv_vcpu_aia_imsic_update arch/riscv/kvm/aia_imsic.c:801 kvm_riscv_vcpu_aia_update arch/riscv/kvm/aia_device.c:493 kvm_arch_vcpu_ioctl_run arch/riscv/kvm/vcpu.c:927 ... Add a guard to skip the IMSIC update path when imsic_state is NULL. This allows the vCPU run loop to continue safely. This issue was discovered during fuzzing of RISC-V KVM code. Fixes: db8b7e97d6137a ("RISC-V: KVM: Add in-kernel virtualization of AIA IM= SIC") Signed-off-by: Jiakai Xu Signed-off-by: Jiakai Xu Reviewed-by: Anup Patel --- arch/riscv/kvm/aia_imsic.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c index e597e86491c3b..a7d387e280d49 100644 --- a/arch/riscv/kvm/aia_imsic.c +++ b/arch/riscv/kvm/aia_imsic.c @@ -797,6 +797,10 @@ int kvm_riscv_vcpu_aia_imsic_update(struct kvm_vcpu *v= cpu) if (kvm->arch.aia.mode =3D=3D KVM_DEV_RISCV_AIA_MODE_EMUL) return 1; =20 + /* IMSIC vCPU state may not be initialized yet */ + if (!imsic) + return 1; + /* Read old IMSIC VS-file details */ read_lock_irqsave(&imsic->vsfile_lock, flags); old_vsfile_hgei =3D imsic->vsfile_hgei; --=20 2.34.1