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Tue, 05 Aug 2025 03:54:04 -0700 (PDT) From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= To: kvm-riscv@lists.infradead.org Cc: kvm@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Anup Patel , Atish Patra , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Daniel Henrique Barboza , stable@vger.kernel.org Subject: [PATCH] RISC-V: KVM: fix stack overrun when loading vlenb Date: Tue, 5 Aug 2025 12:44:21 +0200 Message-ID: <20250805104418.196023-4-rkrcmar@ventanamicro.com> X-Mailer: git-send-email 2.50.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The userspace load can put up to 2048 bits into an xlen bit stack buffer. We want only xlen bits, so check the size beforehand. Fixes: 2fa290372dfe ("RISC-V: KVM: add 'vlenb' Vector CSR") Cc: Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 Reviewed-by: Daniel Henrique Barboza Reviewed-by: Nutty Liu --- arch/riscv/kvm/vcpu_vector.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/riscv/kvm/vcpu_vector.c b/arch/riscv/kvm/vcpu_vector.c index a5f88cb717f3..05f3cc2d8e31 100644 --- a/arch/riscv/kvm/vcpu_vector.c +++ b/arch/riscv/kvm/vcpu_vector.c @@ -182,6 +182,8 @@ int kvm_riscv_vcpu_set_reg_vector(struct kvm_vcpu *vcpu, struct kvm_cpu_context *cntx =3D &vcpu->arch.guest_context; unsigned long reg_val; =20 + if (reg_size !=3D sizeof(reg_val)) + return -EINVAL; if (copy_from_user(®_val, uaddr, reg_size)) return -EFAULT; if (reg_val !=3D cntx->vector.vlenb) --=20 2.50.0