From nobody Wed Apr 8 04:44:48 2026 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (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 DDEBA248F73 for ; Tue, 10 Mar 2026 23:48:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773186523; cv=none; b=lq4disjY4+a9tcPNFAGUcr4yp8SbWq99ymhSZCao5nY1Eh5hfwj0uXzckWL3Yt6kIbbdvyujNBdRvZf0JPBATHdKPLH+BwGmKviUWXEfEAHYk+gPmbf1XTun31mIgYjg0YnOMwNlO+UOdacPkx294uz8QYc95oiDiYxdnI57cMM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773186523; c=relaxed/simple; bh=b+5ch2gAT5ERnn5NbXyhxSiq0SzA5rU9kaWO6cIeDtw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=TP/9RmwH0rEDHukhcYj77zdFXF8W75zcj1BM3Lo9YOj2fWsVt2VP46R+l3kKxkSzptN2PITQLp6Ibs37O2czuN9YfU+Hoa9IMUIbKpSDFZmCAisi3pPOVrHseo27js33iskjMdm8uQSSMvntpydlKmK6IAhCWv0mWjIp9PgzgCU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Ugiyn73l; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Ugiyn73l" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2ae59e057f1so102110825ad.1 for ; Tue, 10 Mar 2026 16:48:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1773186521; x=1773791321; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=JjsNKd0HOBrtHRwBgNBz3zDbDewW5UJ/SeZaXW6KVIw=; b=Ugiyn73ljZN6gsvnDiGosw0D/cjoKNKaAX4c9DV41u/qeFOwe+wgOZ6TV9caZNNGRx NIp8xbaHRUEbmOf0qBLe/MU089Cn5HHkis4rX/B7W6lrwfw+ublRZbcH/SVpJav43GWx lvhl3ES70vsH1aoxnNGtrejvuoUXqaErVfvXFMJoBmPpbFGG4arOOimQKwbDTPxjp6VQ Jjyw+HasfZLX6vD/9+5VX8C30iyh+tKPEJe2uMOu8FqHUcdtNRTeoF0JdLg9rQuo/C37 7FsKwPCLky4YlZac/94bTLs8XoACsrC4hcJRcT6GFSBo3lHDtu+J48O0JiuLCXcM4gQG EPFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773186521; x=1773791321; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=JjsNKd0HOBrtHRwBgNBz3zDbDewW5UJ/SeZaXW6KVIw=; b=BQF+z6We1iJxNfI2A+CzJ4qPrMoxxNFQZLLKyI2OBEzbDdUr6+QZ04mWgZQDcmVuAo aSHQ0yqXoiwfblxg1q4bGPsc56x8jsJu7ZyTmc/3CG+LFZ9bd8OnM9vCU12cc32uPo09 1qLFZfjkYanyx3m6GykJOUanY8+S1CdyrJpkqpV5TPD6iLqJIL5Lj2Y5Pcxv2uelwItp tqt+YHdBUDfLD9HqdswQz8WOzzNGiid6+gT5p+WPVCYtbCeJHbl3svEdZgRFuSvtH/68 MGW7n7HJXPQPBYW0woYxDQqwvZQTq9un/qxu30CEJgdDzZL0F3BwcoA+d/C7r3k0R6kY 27aA== X-Forwarded-Encrypted: i=1; AJvYcCXso2LU48BMiC240pcFIgWJp1TDEj78q5QxO14Sm3N+fzzUSNWCLTMcQEv7a9kRRJXHsGCaO23FTY2DXoA=@vger.kernel.org X-Gm-Message-State: AOJu0Yz+6T0rzf2c38zP6PYb2Vo+bL6lXCRK9tzJmzSvjCEYtFRwYhdI Wv3xRan4pVcTAv4beNb3vu6aqRrIg0zJYKySQoKNTsdham63tAub9RuE43N95s/3kqPjZnEiEC5 +r0yOHg== X-Received: from pfbhg13.prod.google.com ([2002:a05:6a00:860d:b0:827:3eb4:a39a]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:46c5:b0:398:c2d8:14c with SMTP id adf61e73a8af0-398c5e6e2bcmr328641637.7.1773186520900; Tue, 10 Mar 2026 16:48:40 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 10 Mar 2026 16:48:11 -0700 In-Reply-To: <20260310234829.2608037-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260310234829.2608037-1-seanjc@google.com> X-Mailer: git-send-email 2.53.0.473.g4a7958ca14-goog Message-ID: <20260310234829.2608037-4-seanjc@google.com> Subject: [PATCH 03/21] KVM: SEV: Protect *all* of sev_mem_enc_register_region() with kvm->lock From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jethro Beekman , Alexander Potapenko , "=?UTF-8?q?Carlos=20L=C3=B3pez?=" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Take and hold kvm->lock for before checking sev_guest() in sev_mem_enc_register_region(), as sev_guest() isn't stable unless kvm->lock is held (or KVM can guarantee KVM_SEV_INIT{2} has completed and can't rollack state). If KVM_SEV_INIT{2} fails, KVM can end up trying to add to a not-yet-initialized sev->regions_list, e.g. triggering a #GP Oops: general protection fault, probably for non-canonical address 0xdfff= fc0000000000: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 110 UID: 0 PID: 72717 Comm: syz.15.11462 Tainted: G U W O = 6.16.0-smp-DEV #1 NONE Tainted: [U]=3DUSER, [W]=3DWARN, [O]=3DOOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.52.0-0 1= 0/28/2024 RIP: 0010:sev_mem_enc_register_region+0x3f0/0x4f0 ../include/linux/list.h= :83 Code: <41> 80 3c 04 00 74 08 4c 89 ff e8 f1 c7 a2 00 49 39 ed 0f 84 c6 00 RSP: 0018:ffff88838647fbb8 EFLAGS: 00010256 RAX: dffffc0000000000 RBX: 1ffff92015cf1e0b RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000001000 RDI: ffff888367870000 RBP: ffffc900ae78f050 R08: ffffea000d9e0007 R09: 1ffffd4001b3c000 R10: dffffc0000000000 R11: fffff94001b3c001 R12: 0000000000000000 R13: ffff8982ab0bde00 R14: ffffc900ae78f058 R15: 0000000000000000 FS: 00007f34e9dc66c0(0000) GS:ffff89ee64d33000(0000) knlGS:0000000000000= 000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fe180adef98 CR3: 000000047210e000 CR4: 0000000000350ef0 Call Trace: kvm_arch_vm_ioctl+0xa72/0x1240 ../arch/x86/kvm/x86.c:7371 kvm_vm_ioctl+0x649/0x990 ../virt/kvm/kvm_main.c:5363 __se_sys_ioctl+0x101/0x170 ../fs/ioctl.c:51 do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x6f/0x1f0 ../arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f34e9f7e9a9 Code: <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f34e9dc6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f34ea1a6080 RCX: 00007f34e9f7e9a9 RDX: 0000200000000280 RSI: 000000008010aebb RDI: 0000000000000007 RBP: 00007f34ea000d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f34ea1a6080 R15: 00007ffce77197a8 with a syzlang reproducer that looks like: syz_kvm_add_vcpu$x86(0x0, &(0x7f0000000040)=3D{0x0, &(0x7f0000000180)=3DA= NY=3D[], 0x70}) (async) syz_kvm_add_vcpu$x86(0x0, &(0x7f0000000080)=3D{0x0, &(0x7f0000000180)=3DA= NY=3D[@ANYBLOB=3D"..."], 0x4f}) (async) r0 =3D openat$kvm(0xffffffffffffff9c, &(0x7f0000000200), 0x0, 0x0) r1 =3D ioctl$KVM_CREATE_VM(r0, 0xae01, 0x0) r2 =3D openat$kvm(0xffffffffffffff9c, &(0x7f0000000240), 0x0, 0x0) r3 =3D ioctl$KVM_CREATE_VM(r2, 0xae01, 0x0) ioctl$KVM_SET_CLOCK(r3, 0xc008aeba, &(0x7f0000000040)=3D{0x1, 0x8, 0x0, 0= x5625e9b0}) (async) ioctl$KVM_SET_PIT2(r3, 0x8010aebb, &(0x7f0000000280)=3D{[...], 0x5}) (asy= nc) ioctl$KVM_SET_PIT2(r1, 0x4070aea0, 0x0) (async) r4 =3D ioctl$KVM_CREATE_VM(0xffffffffffffffff, 0xae01, 0x0) openat$kvm(0xffffffffffffff9c, 0x0, 0x0, 0x0) (async) ioctl$KVM_SET_USER_MEMORY_REGION(r4, 0x4020ae46, &(0x7f0000000400)=3D{0x0= , 0x0, 0x0, 0x2000, &(0x7f0000001000/0x2000)=3Dnil}) (async) r5 =3D ioctl$KVM_CREATE_VCPU(r4, 0xae41, 0x2) close(r0) (async) openat$kvm(0xffffffffffffff9c, &(0x7f0000000000), 0x8000, 0x0) (async) ioctl$KVM_SET_GUEST_DEBUG(r5, 0x4048ae9b, &(0x7f0000000300)=3D{0x4376ea83= 0d46549b, 0x0, [0x46, 0x0, 0x0, 0x0, 0x0, 0x1000]}) (async) ioctl$KVM_RUN(r5, 0xae80, 0x0) Opportunistically use guard() to avoid having to define a new error label and goto usage. Fixes: 1e80fdc09d12 ("KVM: SVM: Pin guest memory when SEV is active") Cc: stable@vger.kernel.org Reported-by: Alexander Potapenko Tested-by: Alexander Potapenko Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index fa319a66938c..7da040baba1c 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2704,6 +2704,8 @@ int sev_mem_enc_register_region(struct kvm *kvm, struct enc_region *region; int ret =3D 0; =20 + guard(mutex)(&kvm->lock); + if (!sev_guest(kvm)) return -ENOTTY; =20 @@ -2718,12 +2720,10 @@ int sev_mem_enc_register_region(struct kvm *kvm, if (!region) return -ENOMEM; =20 - mutex_lock(&kvm->lock); region->pages =3D sev_pin_memory(kvm, range->addr, range->size, ®ion->= npages, FOLL_WRITE | FOLL_LONGTERM); if (IS_ERR(region->pages)) { ret =3D PTR_ERR(region->pages); - mutex_unlock(&kvm->lock); goto e_free; } =20 @@ -2741,8 +2741,6 @@ int sev_mem_enc_register_region(struct kvm *kvm, region->size =3D range->size; =20 list_add_tail(®ion->list, &sev->regions_list); - mutex_unlock(&kvm->lock); - return ret; =20 e_free: --=20 2.53.0.473.g4a7958ca14-goog