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Date: Mon, 24 Jan 2022 19:42:15 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Alexey Kardashevskiy <aik@...abs.ru>, Fabiano Rosas <farosas@...ux.ibm.com>, Michael Ellerman <mpe@...erman.id.au>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.16 0746/1039] KVM: PPC: Book3S: Suppress failed alloc warning in H_COPY_TOFROM_GUEST From: Alexey Kardashevskiy <aik@...abs.ru> [ Upstream commit 792020907b11c6f9246c21977cab3bad985ae4b6 ] H_COPY_TOFROM_GUEST is an hcall for an upper level VM to access its nested VMs memory. The userspace can trigger WARN_ON_ONCE(!(gfp & __GFP_NOWARN)) in __alloc_pages() by constructing a tiny VM which only does H_COPY_TOFROM_GUEST with a too big GPR9 (number of bytes to copy). This silences the warning by adding __GFP_NOWARN. Spotted by syzkaller. Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru> Reviewed-by: Fabiano Rosas <farosas@...ux.ibm.com> Signed-off-by: Michael Ellerman <mpe@...erman.id.au> Link: https://lore.kernel.org/r/20210901084550.1658699-1-aik@ozlabs.ru Signed-off-by: Sasha Levin <sashal@...nel.org> --- arch/powerpc/kvm/book3s_hv_nested.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index ed8a2c9f56299..89295b52a97c3 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -582,7 +582,7 @@ long kvmhv_copy_tofrom_guest_nested(struct kvm_vcpu *vcpu) if (eaddr & (0xFFFUL << 52)) return H_PARAMETER; - buf = kzalloc(n, GFP_KERNEL); + buf = kzalloc(n, GFP_KERNEL | __GFP_NOWARN); if (!buf) return H_NO_MEM; -- 2.34.1
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