linux-kernel - [PATCH] RISC-V: KVM: Fix null pointer dereference in kvm_riscv_aia_imsic_rw

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20260127072219.3366607-1-xujiakai2025@iscas.ac.cn>
Date: Tue, 27 Jan 2026 07:22:19 +0000
From: Jiakai Xu <jiakaipeanut@...il.com>
To: linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	kvm-riscv@...ts.infradead.org,
	kvm@...r.kernel.org
Cc: Anup Patel <anup@...infault.org>,
	Atish Patra <atish.patra@...ux.dev>,
	Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Jiakai Xu <xujiakai2025@...as.ac.cn>,
	Jiakai Xu <jiakaiPeanut@...il.com>
Subject: [PATCH] RISC-V: KVM: Fix null pointer dereference in kvm_riscv_aia_imsic_rw_attr()

Add a null pointer check for imsic_state before dereferencing it in
kvm_riscv_aia_imsic_rw_attr(). While the function checks that the
vcpu exists, it doesn't verify that the vcpu's imsic_state has been
initialized, leading to a null pointer dereference when accessed.

The crash manifests as:
  Unable to handle kernel paging request at virtual address
  dfffffff00000006
  ...
  kvm_riscv_aia_imsic_rw_attr+0x2d8/0x854 arch/riscv/kvm/aia_imsic.c:958
  aia_set_attr+0x2ee/0x1726 arch/riscv/kvm/aia_device.c:354
  kvm_device_ioctl_attr virt/kvm/kvm_main.c:4744 [inline]
  kvm_device_ioctl+0x296/0x374 virt/kvm/kvm_main.c:4761
  vfs_ioctl fs/ioctl.c:51 [inline]
  ...

The fix adds a check to return -ENODEV if imsic_state is NULL and moves 
isel assignment after imsic_state NULL check.

Fixes: 5463091a51cfaa ("RISC-V: KVM: Expose IMSIC registers as attributes of AIA irqchip")
Signed-off-by: Jiakai Xu <xujiakai2025@...as.ac.cn>
Signed-off-by: Jiakai Xu <jiakaiPeanut@...il.com>
---
 arch/riscv/kvm/aia_imsic.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kvm/aia_imsic.c b/arch/riscv/kvm/aia_imsic.c
index e597e86491c3b..bd7081e70036d 100644
--- a/arch/riscv/kvm/aia_imsic.c
+++ b/arch/riscv/kvm/aia_imsic.c
@@ -952,8 +952,10 @@ int kvm_riscv_aia_imsic_rw_attr(struct kvm *kvm, unsigned long type,
 	if (!vcpu)
 		return -ENODEV;

-	isel = KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type);
 	imsic = vcpu->arch.aia_context.imsic_state;
+	if (!imsic)
+		return -ENODEV;
+	isel = KVM_DEV_RISCV_AIA_IMSIC_GET_ISEL(type);

 	read_lock_irqsave(&imsic->vsfile_lock, flags);

-- 
2.34.1