From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D02C129CE7; Wed, 2 Oct 2024 13:54:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727877253; cv=none; b=rx1Cgb59exIw40qZVt6s/XbLST+vDOvP5RzbGOS7fFjd6XGqHkF+2NRJA/ZVzV9Gpgehvic2OEOXR+QpOV/WWF9mEuc9729OJufDwWgoOX7Vm9hu9sBUET5UiVfsPF3BebiPHy87VOTO52UDpXaErTJl8lNEfwdV8+uYOQZW5wI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727877253; c=relaxed/simple; bh=s6OOnHhmHSurP2eNHY7zUDXn+R+916O03eMVNr01QzU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jUY6RSU8FqKcdEkJmQxPJtbG+Rcgyg6uK2KshzBzNp7fFOAt7kcAHBTUpquNj69R3oPXwN6XyGovqYSJdS3JwUVaPUgK5aOIy4lrzoc+o/z7GzZX8h6Hdvjp7s6W59AfGBy4T+EEEGVo2GqqvbsXjhjOdNgxAdiee6Y94zh+0mQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ym3hUGqh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ym3hUGqh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5993EC4CEE2; Wed, 2 Oct 2024 13:54:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1727877253; bh=s6OOnHhmHSurP2eNHY7zUDXn+R+916O03eMVNr01QzU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ym3hUGqhDz+ZxCyKeAVtBNYROzY3HI9RsB07KJAa1a1t9apjEEgNLk0TjKv8xtzwF eVKkfCdBtrcGu6JKSWsRYzj6gsqd+jbxAPsEFwQSJ/Tp8GPY/gNQCGfj2Y/8qS+qj8 Js1ZsurnXez6z5aqrOnGAOemMoRZyS8SAu1wOQEw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Anup Patel , Anup Patel , Sasha Levin Subject: [PATCH 6.10 020/634] RISC-V: KVM: Dont zero-out PMU snapshot area before freeing data Date: Wed, 2 Oct 2024 14:52:00 +0200 Message-ID: <20241002125811.892110733@linuxfoundation.org> X-Mailer: git-send-email 2.46.2 In-Reply-To: <20241002125811.070689334@linuxfoundation.org> References: <20241002125811.070689334@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Anup Patel [ Upstream commit 47d40d93292d9cff8dabb735bed83d930fa03950 ] With the latest Linux-6.11-rc3, the below NULL pointer crash is observed when SBI PMU snapshot is enabled for the guest and the guest is forcefully powered-off. Unable to handle kernel NULL pointer dereference at virtual address 0000000000000508 Oops [#1] Modules linked in: kvm CPU: 0 UID: 0 PID: 61 Comm: term-poll Not tainted 6.11.0-rc3-00018-g44d7178dd77a #3 Hardware name: riscv-virtio,qemu (DT) epc : __kvm_write_guest_page+0x94/0xa6 [kvm] ra : __kvm_write_guest_page+0x54/0xa6 [kvm] epc : ffffffff01590e98 ra : ffffffff01590e58 sp : ffff8f80001f39b0 gp : ffffffff81512a60 tp : ffffaf80024872c0 t0 : ffffaf800247e000 t1 : 00000000000007e0 t2 : 0000000000000000 s0 : ffff8f80001f39f0 s1 : 00007fff89ac4000 a0 : ffffffff015dd7e8 a1 : 0000000000000086 a2 : 0000000000000000 a3 : ffffaf8000000000 a4 : ffffaf80024882c0 a5 : 0000000000000000 a6 : ffffaf800328d780 a7 : 00000000000001cc s2 : ffffaf800197bd00 s3 : 00000000000828c4 s4 : ffffaf800248c000 s5 : ffffaf800247d000 s6 : 0000000000001000 s7 : 0000000000001000 s8 : 0000000000000000 s9 : 00007fff861fd500 s10: 0000000000000001 s11: 0000000000800000 t3 : 00000000000004d3 t4 : 00000000000004d3 t5 : ffffffff814126e0 t6 : ffffffff81412700 status: 0000000200000120 badaddr: 0000000000000508 cause: 000000000000000d [] __kvm_write_guest_page+0x94/0xa6 [kvm] [] kvm_vcpu_write_guest+0x56/0x90 [kvm] [] kvm_pmu_clear_snapshot_area+0x42/0x7e [kvm] [] kvm_riscv_vcpu_pmu_deinit.part.0+0xe0/0x14e [kvm] [] kvm_riscv_vcpu_pmu_deinit+0x1a/0x24 [kvm] [] kvm_arch_vcpu_destroy+0x28/0x4c [kvm] [] kvm_destroy_vcpus+0x5a/0xda [kvm] [] kvm_arch_destroy_vm+0x14/0x28 [kvm] [] kvm_destroy_vm+0x168/0x2a0 [kvm] [] kvm_put_kvm+0x3c/0x58 [kvm] [] kvm_vm_release+0x22/0x2e [kvm] Clearly, the kvm_vcpu_write_guest() function is crashing because it is being called from kvm_pmu_clear_snapshot_area() upon guest tear down. To address the above issue, simplify the kvm_pmu_clear_snapshot_area() to not zero-out PMU snapshot area from kvm_pmu_clear_snapshot_area() because the guest is anyway being tore down. The kvm_pmu_clear_snapshot_area() is also called when guest changes PMU snapshot area of a VCPU but even in this case the previous PMU snaphsot area must not be zeroed-out because the guest might have reclaimed the pervious PMU snapshot area for some other purpose. Fixes: c2f41ddbcdd7 ("RISC-V: KVM: Implement SBI PMU Snapshot feature") Signed-off-by: Anup Patel Link: https://lore.kernel.org/r/20240815170907.2792229-1-apatel@ventanamicro.com Signed-off-by: Anup Patel Signed-off-by: Sasha Levin --- arch/riscv/kvm/vcpu_pmu.c | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-) diff --git a/arch/riscv/kvm/vcpu_pmu.c b/arch/riscv/kvm/vcpu_pmu.c index bcf41d6e0df0e..2707a51b082ca 100644 --- a/arch/riscv/kvm/vcpu_pmu.c +++ b/arch/riscv/kvm/vcpu_pmu.c @@ -391,19 +391,9 @@ int kvm_riscv_vcpu_pmu_read_hpm(struct kvm_vcpu *vcpu, unsigned int csr_num, static void kvm_pmu_clear_snapshot_area(struct kvm_vcpu *vcpu) { struct kvm_pmu *kvpmu = vcpu_to_pmu(vcpu); - int snapshot_area_size = sizeof(struct riscv_pmu_snapshot_data); - if (kvpmu->sdata) { - if (kvpmu->snapshot_addr != INVALID_GPA) { - memset(kvpmu->sdata, 0, snapshot_area_size); - kvm_vcpu_write_guest(vcpu, kvpmu->snapshot_addr, - kvpmu->sdata, snapshot_area_size); - } else { - pr_warn("snapshot address invalid\n"); - } - kfree(kvpmu->sdata); - kvpmu->sdata = NULL; - } + kfree(kvpmu->sdata); + kvpmu->sdata = NULL; kvpmu->snapshot_addr = INVALID_GPA; } -- 2.43.0