From 86ef58a4e35e8fa66afb5898cf6dec6a3bb29f67 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Tue, 28 Feb 2017 18:32:48 -0800 Subject: nfit, libnvdimm: fix interleave set cookie calculation The interleave-set cookie is a sum that sanity checks the composition of an interleave set has not changed from when the namespace was initially created. The checksum is calculated by sorting the DIMMs by their location in the interleave-set. The comparison for the sort must be 64-bit wide, not byte-by-byte as performed by memcmp() in the broken case. Fix the implementation to accept correct cookie values in addition to the Linux "memcmp" order cookies, but only allow correct cookies to be generated going forward. It does mean that namespaces created by third-party-tooling, or created by newer kernels with this fix, will not validate on older kernels. However, there are a couple mitigating conditions: 1/ platforms with namespace-label capable NVDIMMs are not widely available. 2/ interleave-sets with a single-dimm are by definition not affected (nothing to sort). This covers the QEMU-KVM NVDIMM emulation case. The cookie stored in the namespace label will be fixed by any write the namespace label, the most straightforward way to achieve this is to write to the "alt_name" attribute of a namespace in sysfs. Cc: Fixes: eaf961536e16 ("libnvdimm, nfit: add interleave-set state-tracking infrastructure") Reported-by: Nicholas Moulin Tested-by: Nicholas Moulin Signed-off-by: Dan Williams --- include/linux/libnvdimm.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/libnvdimm.h b/include/linux/libnvdimm.h index 8458c5351e56..77e7af32543f 100644 --- a/include/linux/libnvdimm.h +++ b/include/linux/libnvdimm.h @@ -70,6 +70,8 @@ struct nd_cmd_desc { struct nd_interleave_set { u64 cookie; + /* compatibility with initial buggy Linux implementation */ + u64 altcookie; }; struct nd_mapping_desc { -- cgit v1.2.3-58-ga151