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 214DB406D30; Sat, 28 Feb 2026 17:44:05 +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=1772300645; cv=none; b=co7/taRn3BNSQg0Rt6AwxcfGjNls+PW4HSCUhqd03DTkBx9thzzzKcT66rDe6anUKFwhRuJKmP/ZitEYL4DZJUwbjAb4q+m2N0VTyAqmtvSrmRVkudGsuNbXkn8Al+elfWnHA5b7OIeuUBoVfdAoOJNlA7Q8NCyAPGolvai68Do= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300645; c=relaxed/simple; bh=MbuABjn9H9HKfHNv7nGjfbWLKR6u++7irBa3GmCmfZ4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rsTiUXyMHFYcHe9eq9T87Wz1ELELphVW44aq824WPGZ367bnLyANNiRLPAn4dY/H6EpevRbkLRfqXoojSJPU9IL+vjcgVAWfaZaFL8mf1spNTdB58WIp9MeaCV8SXD51uVjIadgltNIcpw9erKdqTOfnznBPpvZXBNLkGQdO43s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ms1NaqP2; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ms1NaqP2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68911C19424; Sat, 28 Feb 2026 17:44:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772300645; bh=MbuABjn9H9HKfHNv7nGjfbWLKR6u++7irBa3GmCmfZ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ms1NaqP2fhY07hwI5kmwqa7QjCwWC1enFCUDtTv7Q02G3EtBRYYo5LjoxwTRo5kLY Vws8utbGTT0LVQz/8i3r3hLpDHx9AkVcFsN3fXRZ1pyg9jRSQzT5BkzKKqg4VZoBJt gGIuDS661pjgSKZouAbaM+hHGPOa0/8zO1nrKVsqiCWXTyTXvrlvvSRWRAGQaNsEp2 r4qXdua1LIW6seWzDiGscSo5fhVk8o9kzRU54bx3KbBQN6+lhq3c/+ayFbV8x3R7FU OTr2uf7Ej9UE2Oo/9q2yR9heMtSUMDoQy9PMn5SynRa6TlfvA8bLG6Q/O0qcgYxa8C Iz6KoY19fBvOg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasiliy Kovalev , Sean Christopherson , Sasha Levin Subject: [PATCH 6.19 686/844] KVM: x86: Add SRCU protection for reading PDPTRs in __get_sregs2() Date: Sat, 28 Feb 2026 12:29:59 -0500 Message-ID: <20260228173244.1509663-687-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228173244.1509663-1-sashal@kernel.org> References: <20260228173244.1509663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Vasiliy Kovalev [ Upstream commit 95d848dc7e639988dbb385a8cba9b484607cf98c ] Add SRCU read-side protection when reading PDPTR registers in __get_sregs2(). Reading PDPTRs may trigger access to guest memory: kvm_pdptr_read() -> svm_cache_reg() -> load_pdptrs() -> kvm_vcpu_read_guest_page() -> kvm_vcpu_gfn_to_memslot() kvm_vcpu_gfn_to_memslot() dereferences memslots via __kvm_memslots(), which uses srcu_dereference_check() and requires either kvm->srcu or kvm->slots_lock to be held. Currently only vcpu->mutex is held, triggering lockdep warning: ============================= WARNING: suspicious RCU usage in kvm_vcpu_gfn_to_memslot 6.12.59+ #3 Not tainted include/linux/kvm_host.h:1062 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz.5.1717/15100: #0: ff1100002f4b00b0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x1d5/0x1590 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xf0/0x120 lib/dump_stack.c:120 lockdep_rcu_suspicious+0x1e3/0x270 kernel/locking/lockdep.c:6824 __kvm_memslots include/linux/kvm_host.h:1062 [inline] __kvm_memslots include/linux/kvm_host.h:1059 [inline] kvm_vcpu_memslots include/linux/kvm_host.h:1076 [inline] kvm_vcpu_gfn_to_memslot+0x518/0x5e0 virt/kvm/kvm_main.c:2617 kvm_vcpu_read_guest_page+0x27/0x50 virt/kvm/kvm_main.c:3302 load_pdptrs+0xff/0x4b0 arch/x86/kvm/x86.c:1065 svm_cache_reg+0x1c9/0x230 arch/x86/kvm/svm/svm.c:1688 kvm_pdptr_read arch/x86/kvm/kvm_cache_regs.h:141 [inline] __get_sregs2 arch/x86/kvm/x86.c:11784 [inline] kvm_arch_vcpu_ioctl+0x3e20/0x4aa0 arch/x86/kvm/x86.c:6279 kvm_vcpu_ioctl+0x856/0x1590 virt/kvm/kvm_main.c:4663 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl fs/ioctl.c:893 [inline] __x64_sys_ioctl+0x18b/0x210 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xbd/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Found by Linux Verification Center (linuxtesting.org) with Syzkaller. Suggested-by: Sean Christopherson Cc: stable@vger.kernel.org Fixes: 6dba94035203 ("KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2") Signed-off-by: Vasiliy Kovalev Link: https://patch.msgid.link/20260123222801.646123-1-kovalev@altlinux.org Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d65ebaed18986..8b12bf0774c77 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12157,9 +12157,11 @@ static void __get_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2) return; if (is_pae_paging(vcpu)) { + kvm_vcpu_srcu_read_lock(vcpu); for (i = 0 ; i < 4 ; i++) sregs2->pdptrs[i] = kvm_pdptr_read(vcpu, i); sregs2->flags |= KVM_SREGS2_FLAGS_PDPTRS_VALID; + kvm_vcpu_srcu_read_unlock(vcpu); } } -- 2.51.0