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Subject[PATCH 5.4 14/98] KVM: PPC: Book3S HV: XIVE: Fix possible oops when accessing ESB page
Date
From: Cédric Le Goater <clg@kaod.org>

commit 75b49620267c700f0a07fec7f27f69852db70e46 upstream.

When accessing the ESB page of a source interrupt, the fault handler
will retrieve the page address from the XIVE interrupt 'xive_irq_data'
structure. If the associated KVM XIVE interrupt is not valid, that is
not allocated at the HW level for some reason, the fault handler will
dereference a NULL pointer leading to the oops below :

WARNING: CPU: 40 PID: 59101 at arch/powerpc/kvm/book3s_xive_native.c:259 xive_native_esb_fault+0xe4/0x240 [kvm]
CPU: 40 PID: 59101 Comm: qemu-system-ppc Kdump: loaded Tainted: G W --------- - - 4.18.0-240.el8.ppc64le #1
NIP: c00800000e949fac LR: c00000000044b164 CTR: c00800000e949ec8
REGS: c000001f69617840 TRAP: 0700 Tainted: G W --------- - - (4.18.0-240.el8.ppc64le)
MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 44044282 XER: 00000000
CFAR: c00000000044b160 IRQMASK: 0
GPR00: c00000000044b164 c000001f69617ac0 c00800000e96e000 c000001f69617c10
GPR04: 05faa2b21e000080 0000000000000000 0000000000000005 ffffffffffffffff
GPR08: 0000000000000000 0000000000000001 0000000000000000 0000000000000001
GPR12: c00800000e949ec8 c000001ffffd3400 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 c000001f5c065160 c000000001c76f90
GPR24: c000001f06f20000 c000001f5c065100 0000000000000008 c000001f0eb98c78
GPR28: c000001dcab40000 c000001dcab403d8 c000001f69617c10 0000000000000011
NIP [c00800000e949fac] xive_native_esb_fault+0xe4/0x240 [kvm]
LR [c00000000044b164] __do_fault+0x64/0x220
Call Trace:
[c000001f69617ac0] [0000000137a5dc20] 0x137a5dc20 (unreliable)
[c000001f69617b50] [c00000000044b164] __do_fault+0x64/0x220
[c000001f69617b90] [c000000000453838] do_fault+0x218/0x930
[c000001f69617bf0] [c000000000456f50] __handle_mm_fault+0x350/0xdf0
[c000001f69617cd0] [c000000000457b1c] handle_mm_fault+0x12c/0x310
[c000001f69617d10] [c00000000007ef44] __do_page_fault+0x264/0xbb0
[c000001f69617df0] [c00000000007f8c8] do_page_fault+0x38/0xd0
[c000001f69617e30] [c00000000000a714] handle_page_fault+0x18/0x38
Instruction dump:
40c2fff0 7c2004ac 2fa90000 409e0118 73e90001 41820080 e8bd0008 7c2004ac
7ca90074 39400000 915c0000 7929d182 <0b090000> 2fa50000 419e0080 e89e0018
---[ end trace 66c6ff034c53f64f ]---
xive-kvm: xive_native_esb_fault: accessing invalid ESB page for source 8 !

Fix that by checking the validity of the KVM XIVE interrupt structure.

Fixes: 6520ca64cde7 ("KVM: PPC: Book3S HV: XIVE: Add a mapping for the source ESB pages")
Cc: stable@vger.kernel.org # v5.2+
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201105134713.656160-1-clg@kaod.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/kvm/book3s_xive_native.c | 7 +++++++
1 file changed, 7 insertions(+)

--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -252,6 +252,13 @@ static vm_fault_t xive_native_esb_fault(
}

state = &sb->irq_state[src];
+
+ /* Some sanity checking */
+ if (!state->valid) {
+ pr_devel("%s: source %lx invalid !\n", __func__, irq);
+ return VM_FAULT_SIGBUS;
+ }
+
kvmppc_xive_select_irq(state, &hw_num, &xd);

arch_spin_lock(&sb->lock);

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