This is a note to let you know that I've just added the patch titled
KVM: x86: Check for rmaps allocation
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-check-for-rmaps-allocation.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fffb5323780786c81ba005f8b8603d4a558aad28 Mon Sep 17 00:00:00 2001
From: Nikunj A Dadhania <nikunj@xxxxxxx>
Date: Wed, 5 Jan 2022 09:33:37 +0530
Subject: KVM: x86: Check for rmaps allocation
From: Nikunj A Dadhania <nikunj@xxxxxxx>
commit fffb5323780786c81ba005f8b8603d4a558aad28 upstream.
With TDP MMU being the default now, access to mmu_rmaps_stat debugfs
file causes following oops:
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 7 PID: 3185 Comm: cat Not tainted 5.16.0-rc4+ #204
RIP: 0010:pte_list_count+0x6/0x40
Call Trace:
<TASK>
? kvm_mmu_rmaps_stat_show+0x15e/0x320
seq_read_iter+0x126/0x4b0
? aa_file_perm+0x124/0x490
seq_read+0xf5/0x140
full_proxy_read+0x5c/0x80
vfs_read+0x9f/0x1a0
ksys_read+0x67/0xe0
__x64_sys_read+0x19/0x20
do_syscall_64+0x3b/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fca6fc13912
Return early when rmaps are not present.
Reported-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Tested-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20220105040337.4234-1-nikunj@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 3bcd0662d66f ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file")
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/debugfs.c | 3 +++
1 file changed, 3 insertions(+)
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -95,6 +95,9 @@ static int kvm_mmu_rmaps_stat_show(struc
unsigned int *log[KVM_NR_PAGE_SIZES], *cur;
int i, j, k, l, ret;
+ if (!kvm_memslots_have_rmaps(kvm))
+ return 0;
+
ret = -ENOMEM;
memset(log, 0, sizeof(log));
for (i = 0; i < KVM_NR_PAGE_SIZES; i++) {
Patches currently in stable-queue which might be from nikunj@xxxxxxx are
queue-5.15/kvm-x86-check-for-rmaps-allocation.patch
