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powerpc/papr_scm: Fix an off-by-one check in papr_scm_meta_{get, set}

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A validation check to prevent out of bounds read/write inside
functions papr_scm_meta_{get,set}() is off-by-one that prevent reads
and writes to the last byte of the label area.

This bug manifests as a failure to probe a dimm when libnvdimm is
unable to read the entire config-area as advertised by
ND_CMD_GET_CONFIG_SIZE. This usually happens when there are large
number of namespaces created in the region backed by the dimm and the
label-index spans max possible config-area. An error of the form below
usually reported in the kernel logs:

[  255.293912] nvdimm: probe of nmem0 failed with error -22

The patch fixes these validation checks there by letting libnvdimm
access the entire config-area.

Fixes: 53e80bd042773('powerpc/nvdimm: Add support for multibyte read/write for metadata')
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190927062002.3169-1-vaibhav@linux.ibm.com
This commit is contained in:
Vaibhav Jain 2019-09-27 11:50:02 +05:30 committed by Michael Ellerman
parent da0c9ea146
commit 612ee81b94
1 changed files with 2 additions and 2 deletions
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4
arch/powerpc/platforms/pseries/papr_scm.c
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@ -152,7 +152,7 @@ static int papr_scm_meta_get(struct papr_scm_priv *p,
int len, read;
int64_t ret;
if ((hdr->in_offset + hdr->in_length) >= p->metadata_size)
if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
return -EINVAL;
for (len = hdr->in_length; len; len -= read) {
@ -206,7 +206,7 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
__be64 data_be;
int64_t ret;
if ((hdr->in_offset + hdr->in_length) >= p->metadata_size)
if ((hdr->in_offset + hdr->in_length) > p->metadata_size)
return -EINVAL;
for (len = hdr->in_length; len; len -= wrote) {