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| author | Lukas Gerlach <lukas.gerlach@cispa.de> | 2026-03-03 17:19:41 +0300 |
|---|---|---|
| committer | Anup Patel <anup@brainfault.org> | 2026-03-06 08:50:30 +0300 |
| commit | f9e26fc325411a34555ad07ddf0a19ff72ea06d4 (patch) | |
| tree | 500a0d3fd33182bec11e693aeab46ba8ea2ba472 | |
| parent | b342166cbcf96a8c846db96529e75dc2d2420d58 (diff) | |
| download | linux-f9e26fc325411a34555ad07ddf0a19ff72ea06d4.tar.xz | |
KVM: riscv: Fix Spectre-v1 in ONE_REG register access
User-controlled register indices from the ONE_REG ioctl are used to
index into arrays of register values. Sanitize them with
array_index_nospec() to prevent speculative out-of-bounds access.
Reviewed-by: Radim Krčmář <radim.krcmar@oss.qualcomm.com>
Signed-off-by: Lukas Gerlach <lukas.gerlach@cispa.de>
Link: https://lore.kernel.org/r/20260303-kvm-riscv-spectre-v1-v2-1-192caab8e0dc@cispa.de
Signed-off-by: Anup Patel <anup@brainfault.org>
| -rw-r--r-- | arch/riscv/kvm/vcpu_onereg.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c index e7ab6cb00646..a4c8703a96a9 100644 --- a/arch/riscv/kvm/vcpu_onereg.c +++ b/arch/riscv/kvm/vcpu_onereg.c @@ -10,6 +10,7 @@ #include <linux/bitops.h> #include <linux/errno.h> #include <linux/err.h> +#include <linux/nospec.h> #include <linux/uaccess.h> #include <linux/kvm_host.h> #include <asm/cacheflush.h> @@ -127,6 +128,7 @@ static int kvm_riscv_vcpu_isa_check_host(unsigned long kvm_ext, unsigned long *g kvm_ext >= ARRAY_SIZE(kvm_isa_ext_arr)) return -ENOENT; + kvm_ext = array_index_nospec(kvm_ext, ARRAY_SIZE(kvm_isa_ext_arr)); *guest_ext = kvm_isa_ext_arr[kvm_ext]; switch (*guest_ext) { case RISCV_ISA_EXT_SMNPM: @@ -443,13 +445,16 @@ static int kvm_riscv_vcpu_get_reg_core(struct kvm_vcpu *vcpu, unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_RISCV_CORE); + unsigned long regs_max = sizeof(struct kvm_riscv_core) / sizeof(unsigned long); unsigned long reg_val; if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long)) return -EINVAL; - if (reg_num >= sizeof(struct kvm_riscv_core) / sizeof(unsigned long)) + if (reg_num >= regs_max) return -ENOENT; + reg_num = array_index_nospec(reg_num, regs_max); + if (reg_num == KVM_REG_RISCV_CORE_REG(regs.pc)) reg_val = cntx->sepc; else if (KVM_REG_RISCV_CORE_REG(regs.pc) < reg_num && @@ -476,13 +481,16 @@ static int kvm_riscv_vcpu_set_reg_core(struct kvm_vcpu *vcpu, unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_RISCV_CORE); + unsigned long regs_max = sizeof(struct kvm_riscv_core) / sizeof(unsigned long); unsigned long reg_val; if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long)) return -EINVAL; - if (reg_num >= sizeof(struct kvm_riscv_core) / sizeof(unsigned long)) + if (reg_num >= regs_max) return -ENOENT; + reg_num = array_index_nospec(reg_num, regs_max); + if (copy_from_user(®_val, uaddr, KVM_REG_SIZE(reg->id))) return -EFAULT; @@ -507,10 +515,13 @@ static int kvm_riscv_vcpu_general_get_csr(struct kvm_vcpu *vcpu, unsigned long *out_val) { struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; + unsigned long regs_max = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long); - if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long)) + if (reg_num >= regs_max) return -ENOENT; + reg_num = array_index_nospec(reg_num, regs_max); + if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) { kvm_riscv_vcpu_flush_interrupts(vcpu); *out_val = (csr->hvip >> VSIP_TO_HVIP_SHIFT) & VSIP_VALID_MASK; @@ -526,10 +537,13 @@ static int kvm_riscv_vcpu_general_set_csr(struct kvm_vcpu *vcpu, unsigned long reg_val) { struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr; + unsigned long regs_max = sizeof(struct kvm_riscv_csr) / sizeof(unsigned long); - if (reg_num >= sizeof(struct kvm_riscv_csr) / sizeof(unsigned long)) + if (reg_num >= regs_max) return -ENOENT; + reg_num = array_index_nospec(reg_num, regs_max); + if (reg_num == KVM_REG_RISCV_CSR_REG(sip)) { reg_val &= VSIP_VALID_MASK; reg_val <<= VSIP_TO_HVIP_SHIFT; @@ -548,11 +562,14 @@ static inline int kvm_riscv_vcpu_smstateen_set_csr(struct kvm_vcpu *vcpu, unsigned long reg_val) { struct kvm_vcpu_smstateen_csr *csr = &vcpu->arch.smstateen_csr; + unsigned long regs_max = sizeof(struct kvm_riscv_smstateen_csr) / + sizeof(unsigned long); - if (reg_num >= sizeof(struct kvm_riscv_smstateen_csr) / - sizeof(unsigned long)) + if (reg_num >= regs_max) return -EINVAL; + reg_num = array_index_nospec(reg_num, regs_max); + ((unsigned long *)csr)[reg_num] = reg_val; return 0; } @@ -562,11 +579,14 @@ static int kvm_riscv_vcpu_smstateen_get_csr(struct kvm_vcpu *vcpu, unsigned long *out_val) { struct kvm_vcpu_smstateen_csr *csr = &vcpu->arch.smstateen_csr; + unsigned long regs_max = sizeof(struct kvm_riscv_smstateen_csr) / + sizeof(unsigned long); - if (reg_num >= sizeof(struct kvm_riscv_smstateen_csr) / - sizeof(unsigned long)) + if (reg_num >= regs_max) return -EINVAL; + reg_num = array_index_nospec(reg_num, regs_max); + *out_val = ((unsigned long *)csr)[reg_num]; return 0; } |