| Message ID | 20191212094049.12437-1-will@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 1ce74e96c2407df2b5867e5d45a70aacb8923c14 |
| Headers | show |
| Series | KVM: arm64: Ensure 'params' is initialised when looking up sys register | expand |
On 2019-12-12 09:40, Will Deacon wrote: > Commit 4b927b94d5df ("KVM: arm/arm64: vgic: Introduce > find_reg_by_id()") > introduced 'find_reg_by_id()', which looks up a system register only > if > the 'id' index parameter identifies a valid system register. As part > of > the patch, existing callers of 'find_reg()' were ported over to the > new > interface, but this breaks 'index_to_sys_reg_desc()' in the case that > the > initial lookup in the vCPU target table fails because we will then > call > into 'find_reg()' for the system register table with an uninitialised > 'param' as the key to the lookup. > > GCC 10 is bright enough to spot this (amongst a tonne of false > positives, > but hey!): > > | arch/arm64/kvm/sys_regs.c: In function > ‘index_to_sys_reg_desc.part.0.isra’: > | arch/arm64/kvm/sys_regs.c:983:33: warning: ‘params.Op2’ may be > used uninitialized in this function [-Wmaybe-uninitialized] > | 983 | (u32)(x)->CRn, (u32)(x)->CRm, (u32)(x)->Op2); > | [...] > > Revert the hunk of 4b927b94d5df which breaks > 'index_to_sys_reg_desc()' so > that the old behaviour of checking the index upfront is restored. Huhuh... Well spotted GCC 10! And thanks Will for the fix. > > Cc: <stable@vger.kernel.org> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Vijaya Kumar K <Vijaya.Kumar@cavium.com> > Fixes: 4b927b94d5df ("KVM: arm/arm64: vgic: Introduce > find_reg_by_id()") > Signed-off-by: Will Deacon <will@kernel.org> > --- > arch/arm64/kvm/sys_regs.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 46822afc57e0..01a515e0171e 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -2360,8 +2360,11 @@ static const struct sys_reg_desc > *index_to_sys_reg_desc(struct kvm_vcpu *vcpu, > if ((id & KVM_REG_ARM_COPROC_MASK) != KVM_REG_ARM64_SYSREG) > return NULL; > > + if (!index_to_params(id, ¶ms)) > + return NULL; > + > table = get_target_table(vcpu->arch.target, true, &num); > - r = find_reg_by_id(id, ¶ms, table, num); > + r = find_reg(¶ms, table, num); > if (!r) > r = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); Applied, thanks. M.
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 46822afc57e0..01a515e0171e 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -2360,8 +2360,11 @@ static const struct sys_reg_desc *index_to_sys_reg_desc(struct kvm_vcpu *vcpu, if ((id & KVM_REG_ARM_COPROC_MASK) != KVM_REG_ARM64_SYSREG) return NULL; + if (!index_to_params(id, ¶ms)) + return NULL; + table = get_target_table(vcpu->arch.target, true, &num); - r = find_reg_by_id(id, ¶ms, table, num); + r = find_reg(¶ms, table, num); if (!r) r = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
Commit 4b927b94d5df ("KVM: arm/arm64: vgic: Introduce find_reg_by_id()") introduced 'find_reg_by_id()', which looks up a system register only if the 'id' index parameter identifies a valid system register. As part of the patch, existing callers of 'find_reg()' were ported over to the new interface, but this breaks 'index_to_sys_reg_desc()' in the case that the initial lookup in the vCPU target table fails because we will then call into 'find_reg()' for the system register table with an uninitialised 'param' as the key to the lookup. GCC 10 is bright enough to spot this (amongst a tonne of false positives, but hey!): | arch/arm64/kvm/sys_regs.c: In function ‘index_to_sys_reg_desc.part.0.isra’: | arch/arm64/kvm/sys_regs.c:983:33: warning: ‘params.Op2’ may be used uninitialized in this function [-Wmaybe-uninitialized] | 983 | (u32)(x)->CRn, (u32)(x)->CRm, (u32)(x)->Op2); | [...] Revert the hunk of 4b927b94d5df which breaks 'index_to_sys_reg_desc()' so that the old behaviour of checking the index upfront is restored. Cc: <stable@vger.kernel.org> Cc: Marc Zyngier <maz@kernel.org> Cc: Vijaya Kumar K <Vijaya.Kumar@cavium.com> Fixes: 4b927b94d5df ("KVM: arm/arm64: vgic: Introduce find_reg_by_id()") Signed-off-by: Will Deacon <will@kernel.org> --- arch/arm64/kvm/sys_regs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)