Commit 1ef14328 authored by Frederic Barrat's avatar Frederic Barrat Committed by Sasha Levin

powerpc/mm: Prevent unlikely crash in copro_calculate_slb()

[ Upstream commit d2cf909c ]

If a cxl adapter faults on an invalid address for a kernel context, we
may enter copro_calculate_slb() with a NULL mm pointer (kernel
context) and an effective address which looks like a user
address. Which will cause a crash when dereferencing mm. It is clearly
an AFU bug, but there's no reason to crash either. So return an error,
so that cxl can ack the interrupt with an address error.

Fixes: 73d16a6e ("powerpc/cell: Move data segment faulting code out of cell platform")
Cc: stable@vger.kernel.org # v3.18+
Signed-off-by: default avatarFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Acked-by: default avatarIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 249ed62d
......@@ -102,6 +102,8 @@ int copro_calculate_slb(struct mm_struct *mm, u64 ea, struct copro_slb *slb)
switch (REGION_ID(ea)) {
case USER_REGION_ID:
pr_devel("%s: 0x%llx -- USER_REGION_ID\n", __func__, ea);
if (mm == NULL)
return 1;
psize = get_slice_psize(mm, ea);
ssize = user_segment_size(ea);
vsid = get_vsid(mm->context.id, ea, ssize);
......
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