From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794064165; b=GrHYmkU0mAtt13ZHU+cU563zmpSnND4I2B3gNKSLDwQueqUJ+fi2uOtxa0z8IFzgBVTg qBlB1m/bUAt2IGxtuNRq4WYxyY8w5wZ4/ccarRXYRlTRjHqJcDPxJqvtb/IjN7XWyaruc nDCbP/JgkR6yXEOMk+606hJt7DKvFnjnWgT0Vw4eScZ8nb7X7L0uczPR23fcI1glGl5kE fdSeZH8yhXsMr2VijA63G5ge+8lKiwBkuJF4qRgRuPm0z2FG4wQ82gz3oMbsCl/p9gFkJ L1s+cCsAGrcV9QMbI7tLiPprVseyvY+cwvXKCIS9diJOFuKRzYOSo/cFwAhHLJJ8Y1g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794064165; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=dixo/ybMhqVieDEF0IxBPoV75WNoGx5XXrVMZqWmj0g=; b=kwzXruSlX5GSZQicxuXUgWtalUn9B4i0ze4TSB6cgQUdNOflsVvfxnBUG2yPtmxxEKTv oDNe3jrBbUk6NrmSXnQR6Pt4Ei5FoKsgB1GuHilbsQQluwFg11+OBK6FEeDZfiWBQP0+X 5SGckX6mc+TMlxQnzkQaEYIkoPGM2j2J1WvmtzEUcmzJCT2FuAZPFOhjJD0Scawaf5s2w zr8AGM/CCVbZ0zEadRMFE2gGB/ageQDd+K5OhT412PvyBI5OH1RQpWxdbu71waJICSqT/ a18PjHb4q2k4xQu/gxKmaMEiLekxHaMhtQcWu2r9/tVAD6VcOjGBZN4B128jBal2hrQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=F1+q0BAH; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B195C606A32E; Sat, 7 Nov 2026 15:09:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=F1+q0BAH Received: by smtp.kernel.org (Postfix) with ESMTPSA id 639E61F008A1; Sat, 7 Nov 2026 15:09:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794064164; bh=dixo/ybMhqVieDEF0IxBPoV75WNoGx5XXrVMZqWmj0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=F1+q0BAH6deVrIhlOiyRbGinWcapgx77HV/2LON8McfEaQk1fZGsj9ukHukcl6ITm 6EFbpu43u9x5M/O2HHLgJZehOPHXf5xc/nEmrdeZt1K4Bp3WoMdqyaaeJlxdptFFsY wSAmtBkukik9ac9OZHlK5xK/7X6u+FehG6ZAl+Vc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sashiko AI , Vincent Donnefort , Itaru Kitayama , Wei-Lin Chang , Marc Zyngier , Sasha Levin Subject: [PATCH 7.3 0294/1257] KVM: arm64: ptdump: Check the page tables arent freed when accessing Date: Sat, 7 Nov 2026 08:43:10 -0500 Message-ID: <20261107134947.587199280@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134939.434104957@linuxfoundation.org> References: <20261107134939.434104957@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wei-Lin Chang [ Upstream commit 7d7199bdf77a3a6ed74d0037133f435a7febe97c ] An open debugfs file keeps the KVM structure alive, but does not prevent mmu notifier release from freeing the stage-2 page tables when the VMM’s address space is torn down. Therefore page tables belonging to the mmus could have been freed when a thread opens or reads the ptdump files. Take the mmu_lock and check mmu->pgt is still alive before accessing the page tables. Also for the ipa_range file and stage2_levels file, switch from keeping the pointer to the page tables to keeping the pointer to the mmu. Fixes: 7c4f73548ed1 ("KVM: arm64: Register ptdump with debugfs on guest creation") Reported-by: Sashiko AI Closes: https://lore.kernel.org/kvmarm/20260623144054.B91D21F000E9@smtp.kernel.org/ Reviewed-by: Vincent Donnefort Tested-by: Vincent Donnefort Tested-by: Itaru Kitayama Signed-off-by: Wei-Lin Chang Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260924094951.727352-2-weilin.chang@arm.com Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin --- arch/arm64/kvm/ptdump.c | 43 +++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kvm/ptdump.c b/arch/arm64/kvm/ptdump.c index 69899797dbad8..b5a0584260e8b 100644 --- a/arch/arm64/kvm/ptdump.c +++ b/arch/arm64/kvm/ptdump.c @@ -115,15 +115,28 @@ static int kvm_ptdump_build_levels(struct ptdump_pg_level *level, u32 start_lvl) static struct kvm_ptdump_guest_state *kvm_ptdump_parser_create(struct kvm_s2_mmu *mmu) { + struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); struct kvm_ptdump_guest_state *st; - struct kvm_pgtable *pgtable = mmu->pgt; + s8 start_level; int ret; + /* + * We only need the pgt start level to initialize the ptdump, get it + * while holding the mmu_lock. It's fine if the pgt gets freed + * afterwards, we'll check again when doing the actual dump. + */ + scoped_guard(read_lock, &kvm->mmu_lock) { + if (mmu->pgt) + start_level = mmu->pgt->start_level; + else + return ERR_PTR(-ENOENT); + } + st = kzalloc_obj(struct kvm_ptdump_guest_state, GFP_KERNEL_ACCOUNT); if (!st) return ERR_PTR(-ENOMEM); - ret = kvm_ptdump_build_levels(&st->level[0], pgtable->start_level); + ret = kvm_ptdump_build_levels(&st->level[0], start_level); if (ret) { kfree(st); return ERR_PTR(ret); @@ -149,6 +162,9 @@ static int kvm_ptdump_guest_show(struct seq_file *m, void *unused) }; guard(write_lock)(&kvm->mmu_lock); + if (!mmu->pgt) + return 0; + st->parser_state = (struct ptdump_pg_state) { .marker = &st->ipa_marker[0], .end_address = BIT(mmu->pgt->ia_bits), @@ -211,17 +227,27 @@ static const struct file_operations kvm_ptdump_guest_fops = { static int kvm_pgtable_range_show(struct seq_file *m, void *unused) { - struct kvm_pgtable *pgtable = m->private; + struct kvm_s2_mmu *mmu = m->private; + struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); + + guard(read_lock)(&kvm->mmu_lock); + + if (mmu->pgt) + seq_printf(m, "%2u\n", mmu->pgt->ia_bits); - seq_printf(m, "%2u\n", pgtable->ia_bits); return 0; } static int kvm_pgtable_levels_show(struct seq_file *m, void *unused) { - struct kvm_pgtable *pgtable = m->private; + struct kvm_s2_mmu *mmu = m->private; + struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); + + guard(read_lock)(&kvm->mmu_lock); + + if (mmu->pgt) + seq_printf(m, "%1d\n", KVM_PGTABLE_MAX_LEVELS - mmu->pgt->start_level); - seq_printf(m, "%1d\n", KVM_PGTABLE_MAX_LEVELS - pgtable->start_level); return 0; } @@ -230,15 +256,12 @@ static int kvm_pgtable_debugfs_open(struct inode *m, struct file *file, { struct kvm_s2_mmu *mmu = m->i_private; struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu); - struct kvm_pgtable *pgtable; int ret; if (!kvm_get_kvm_safe(kvm)) return -ENOENT; - pgtable = mmu->pgt; - - ret = single_open(file, show, pgtable); + ret = single_open(file, show, mmu); if (ret < 0) kvm_put_kvm(kvm); return ret; -- 2.53.0