kvm: avoid NULL pointer deref in kvm_write_guest_virt_system
PATCH 1/1 kvm: avoid NULL pointer deref in kvm_write_guest_virt_system
From: Jack Wang <[email protected]>
kvm-unit-test triggered a NULL pointer deref below:
[ 948.518437] kvm [24114]: vcpu0, guest rIP: 0x407ef9 kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x3, nop [ 949.106464] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 949.106707] PGD 0 P4D 0 [ 949.106872] Oops: 0002 [#1] SMP [ 949.107038] CPU: 2 PID: 24126 Comm: qemu-2.7 Not tainted 4.19.77-pserver #4.19.77-1+feature+daily+update+20191005.1625+a4168bb~deb9 [ 949.107283] Hardware name: Dell Inc. Precision Tower 3620/09WH54, BIOS 2.7.3 01/31/2018 [ 949.107549] RIP: 0010:kvm_write_guest_virt_system+0x12/0x40 [kvm] [ 949.107719] Code: c0 5d 41 5c 41 5d 41 5e 83 f8 03 41 0f 94 c0 41 c1 e0 02 e9 b0 ed ff ff 0f 1f 44 00 00 48 89 f0 c6 87 59 56 00 00 01 48 89 d6 <49> c7 00 00 00 00 00 89 ca 49 c7 40 08 00 00 00 00 49 c7 40 10 00 [ 949.108044] RSP: 0018:ffffb31b0a953cb0 EFLAGS: 00010202 [ 949.108216] RAX: 000000000046b4d8 RBX: ffff9e9f415b0000 RCX: 0000000000000008 [ 949.108389] RDX: ffffb31b0a953cc0 RSI: ffffb31b0a953cc0 RDI: ffff9e9f415b0000 [ 949.108562] RBP: 00000000d2e14928 R08: 0000000000000000 R09: 0000000000000000 [ 949.108733] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffc8 [ 949.108907] R13: 0000000000000002 R14: ffff9e9f4f26f2e8 R15: 0000000000000000 [ 949.109079] FS: 00007eff8694c700(0000) GS:ffff9e9f51a80000(0000) knlGS:0000000031415928 [ 949.109318] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 949.109495] CR2: 0000000000000000 CR3: 00000003be53b002 CR4: 00000000003626e0 [ 949.109671] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 949.109845] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 949.110017] Call Trace: [ 949.110186] handle_vmread+0x22b/0x2f0 [kvm_intel] [ 949.110356] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] [ 949.110549] kvm_arch_vcpu_ioctl_run+0xa98/0x1b30 [kvm] [ 949.110725] ? kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.110901] kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.111072] do_vfs_ioctl+0xa2/0x620
The commit introduced the bug is 541ab2aeb282, it has been backported to at least stable 4.14.145+ and 4.19.74+, to fix it, just check the exception not NULL before do the memset. The fix should go to stable.
Fixes 541ab2aeb282 ("KVM: x86: work around leak of uninitialized stack contents")
Signed-off-by Jack Wang <[email protected]>
---
I did the kvm-unit-tests on top of 4.19.77, it no longer crash with the fix, and it applies cleanly to v5.4-rc2.
--- arch/x86/kvm/x86.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
arch/x86/kvm/x86.c +2 -1
@@ -5438,7 +5438,8 @@ int kvm_write_guest_virt_system(struct kvm_vcpu *vcpu, gva_t addr, void *val,* call kvm_inject_page_fault. Ensure that they at least do not leak * uninitialized kernel stack memory into cr2 and error code. */ -memset (exception,0 ,sizeof (*exception)); +if (exception) +memset (exception,0 ,sizeof (*exception));return kvm_write_guest_virt_helper (addr, val, bytes, vcpu,PFERR_WRITE_MASK , exception); }
Signature · 1 line
2.17.1
Paolo Bonzini
maintainerQuoted 30 lines · Jack Wang
From: Jack Wang <[email protected]>
kvm-unit-test triggered a NULL pointer deref below:
[ 948.518437] kvm [24114]: vcpu0, guest rIP: 0x407ef9 kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x3, nop [ 949.106464] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 949.106707] PGD 0 P4D 0 [ 949.106872] Oops: 0002 [#1] SMP [ 949.107038] CPU: 2 PID: 24126 Comm: qemu-2.7 Not tainted 4.19.77-pserver #4.19.77-1+feature+daily+update+20191005.1625+a4168bb~deb9 [ 949.107283] Hardware name: Dell Inc. Precision Tower 3620/09WH54, BIOS 2.7.3 01/31/2018 [ 949.107549] RIP: 0010:kvm_write_guest_virt_system+0x12/0x40 [kvm] [ 949.107719] Code: c0 5d 41 5c 41 5d 41 5e 83 f8 03 41 0f 94 c0 41 c1 e0 02 e9 b0 ed ff ff 0f 1f 44 00 00 48 89 f0 c6 87 59 56 00 00 01 48 89 d6 <49> c7 00 00 00 00 00 89 ca 49 c7 40 08 00 00 00 00 49 c7 40 10 00 [ 949.108044] RSP: 0018:ffffb31b0a953cb0 EFLAGS: 00010202 [ 949.108216] RAX: 000000000046b4d8 RBX: ffff9e9f415b0000 RCX: 0000000000000008 [ 949.108389] RDX: ffffb31b0a953cc0 RSI: ffffb31b0a953cc0 RDI: ffff9e9f415b0000 [ 949.108562] RBP: 00000000d2e14928 R08: 0000000000000000 R09: 0000000000000000 [ 949.108733] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffc8 [ 949.108907] R13: 0000000000000002 R14: ffff9e9f4f26f2e8 R15: 0000000000000000 [ 949.109079] FS: 00007eff8694c700(0000) GS:ffff9e9f51a80000(0000) knlGS:0000000031415928 [ 949.109318] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 949.109495] CR2: 0000000000000000 CR3: 00000003be53b002 CR4: 00000000003626e0 [ 949.109671] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 949.109845] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 949.110017] Call Trace: [ 949.110186] handle_vmread+0x22b/0x2f0 [kvm_intel] [ 949.110356] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] [ 949.110549] kvm_arch_vcpu_ioctl_run+0xa98/0x1b30 [kvm] [ 949.110725] ? kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.110901] kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.111072] do_vfs_ioctl+0xa2/0x620
Quoted 6 lines
The commit introduced the bug is
541ab2aeb282, it has been backported to at least stable 4.14.145+ and 4.19.74+, to fix it, just check the exception not NULL before do the memset. The fix should go to stable.Fixes 541ab2aeb282 ("KVM: x86: work around leak of uninitialized stack contents")Signed-off-by Jack Wang <[email protected]>
Hi Jack,
instead of this, commit f7eea636c3d5 ("KVM: nVMX: handle page fault in vmread", 2019-09-14) should be backported to stable.
Thanks,
Paolo
Quoted 36 lines · Paolo Bonzini
Quoted 34 lines · Jack Wang
From: Jack Wang <[email protected]>
kvm-unit-test triggered a NULL pointer deref below:
[ 948.518437] kvm [24114]: vcpu0, guest rIP: 0x407ef9 kvm_set_msr_common: MSR_IA32_DEBUGCTLMSR 0x3, nop [ 949.106464] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 [ 949.106707] PGD 0 P4D 0 [ 949.106872] Oops: 0002 [#1] SMP [ 949.107038] CPU: 2 PID: 24126 Comm: qemu-2.7 Not tainted 4.19.77-pserver #4.19.77-1+feature+daily+update+20191005.1625+a4168bb~deb9 [ 949.107283] Hardware name: Dell Inc. Precision Tower 3620/09WH54, BIOS 2.7.3 01/31/2018 [ 949.107549] RIP: 0010:kvm_write_guest_virt_system+0x12/0x40 [kvm] [ 949.107719] Code: c0 5d 41 5c 41 5d 41 5e 83 f8 03 41 0f 94 c0 41 c1 e0 02 e9 b0 ed ff ff 0f 1f 44 00 00 48 89 f0 c6 87 59 56 00 00 01 48 89 d6 <49> c7 00 00 00 00 00 89 ca 49 c7 40 08 00 00 00 00 49 c7 40 10 00 [ 949.108044] RSP: 0018:ffffb31b0a953cb0 EFLAGS: 00010202 [ 949.108216] RAX: 000000000046b4d8 RBX: ffff9e9f415b0000 RCX: 0000000000000008 [ 949.108389] RDX: ffffb31b0a953cc0 RSI: ffffb31b0a953cc0 RDI: ffff9e9f415b0000 [ 949.108562] RBP: 00000000d2e14928 R08: 0000000000000000 R09: 0000000000000000 [ 949.108733] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffffffffc8 [ 949.108907] R13: 0000000000000002 R14: ffff9e9f4f26f2e8 R15: 0000000000000000 [ 949.109079] FS: 00007eff8694c700(0000) GS:ffff9e9f51a80000(0000) knlGS:0000000031415928 [ 949.109318] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 949.109495] CR2: 0000000000000000 CR3: 00000003be53b002 CR4: 00000000003626e0 [ 949.109671] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 949.109845] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 949.110017] Call Trace: [ 949.110186] handle_vmread+0x22b/0x2f0 [kvm_intel] [ 949.110356] ? vmexit_fill_RSB+0xc/0x30 [kvm_intel] [ 949.110549] kvm_arch_vcpu_ioctl_run+0xa98/0x1b30 [kvm] [ 949.110725] ? kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.110901] kvm_vcpu_ioctl+0x388/0x5d0 [kvm] [ 949.111072] do_vfs_ioctl+0xa2/0x620The commit introduced the bug is
541ab2aeb282, it has been backported to at least stable 4.14.145+ and 4.19.74+, to fix it, just check the exception not NULL before do the memset. The fix should go to stable.
Quoted 7 lines
Quoted 2 lines
Fixes 541ab2aeb282 ("KVM: x86: work around leak of uninitialized stack contents")Signed-off-by Jack Wang <[email protected]>Hi Jack,
instead of this, commit
f7eea636c3d5("KVM: nVMX: handle page fault in vmread", 2019-09-14) should be backported to stable.
Ok, just checked looks it's a mistake during backport, I will send a fix only to stable.
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.19.y&id=73c31bd920393be70bb30a0b7c6e9c47990c3d3a
Quoted 4 lines
Thanks,
Paolo
Thanks,
Jack