path: root/net/sunrpc
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authorTrond Myklebust <Trond.Myklebust@netapp.com>2013-08-28 13:35:13 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2013-08-28 15:43:43 -0400
commit347e2233b7667e336d9f671f1a52dfa3f0416e2c (patch)
treeed2ee6d0122e3bd3ce3c24ab66bb64fab6ae9de8 /net/sunrpc
parentfa8218def1b1a16f0a410e2c1c767b4738cc81fa (diff)
SUNRPC: Fix memory corruption issue on 32-bit highmem systems
Some architectures, such as ARM-32 do not return the same base address when you call kmap_atomic() twice on the same page. This causes problems for the memmove() call in the XDR helper routine "_shift_data_right_pages()", since it defeats the detection of overlapping memory ranges, and has been seen to corrupt memory. The fix is to distinguish between the case where we're doing an inter-page copy or not. In the former case of we know that the memory ranges cannot possibly overlap, so we can additionally micro-optimise by replacing memmove() with memcpy(). Reported-by: Mark Young <MYoung@nvidia.com> Reported-by: Matt Craighead <mcraighead@nvidia.com> Cc: Bruce Fields <bfields@fieldses.org> Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Tested-by: Matt Craighead <mcraighead@nvidia.com>
Diffstat (limited to 'net/sunrpc')
1 files changed, 6 insertions, 3 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 75edcfad6e2..1504bb11e4f 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -207,10 +207,13 @@ _shift_data_right_pages(struct page **pages, size_t pgto_base,
pgfrom_base -= copy;
vto = kmap_atomic(*pgto);
- vfrom = kmap_atomic(*pgfrom);
- memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
+ if (*pgto != *pgfrom) {
+ vfrom = kmap_atomic(*pgfrom);
+ memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
+ kunmap_atomic(vfrom);
+ } else
+ memmove(vto + pgto_base, vto + pgfrom_base, copy);
- kunmap_atomic(vfrom);
} while ((len -= copy) != 0);