This is a note to let you know that I've just added the patch titled KVM: arm64: Ensure 'params' is initialised when looking up sys register to the 4.19-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-arm64-ensure-params-is-initialised-when-looking-up-sys-register.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 1ce74e96c2407df2b5867e5d45a70aacb8923c14 Mon Sep 17 00:00:00 2001 From: Will Deacon <will@xxxxxxxxxx> Date: Thu, 12 Dec 2019 09:40:49 +0000 Subject: KVM: arm64: Ensure 'params' is initialised when looking up sys register MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Will Deacon <will@xxxxxxxxxx> commit 1ce74e96c2407df2b5867e5d45a70aacb8923c14 upstream. 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. Fixes: 4b927b94d5df ("KVM: arm/arm64: vgic: Introduce find_reg_by_id()") Signed-off-by: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20191212094049.12437-1-will@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/kvm/sys_regs.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -2174,8 +2174,11 @@ static const struct sys_reg_desc *index_ 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)); Patches currently in stable-queue which might be from will@xxxxxxxxxx are queue-4.19/pinctrl-devicetree-avoid-taking-direct-reference-to-.patch queue-4.19/perf-tests-disable-bp_signal-testing-for-arm64.patch queue-4.19/kvm-arm64-ensure-params-is-initialised-when-looking-up-sys-register.patch