| From | Luis Henriques <> | Subject | [PATCH 004/104] SUNRPC: Fix memory corruption issue on 32-bit highmem systems | Date | Mon, 30 Sep 2013 11:09:41 +0100 |
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3.5.7.22 -stable review patch. If anyone has any objections, please let me know.
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From: Trond Myklebust <Trond.Myklebust@netapp.com>
commit 347e2233b7667e336d9f671f1a52dfa3f0416e2c upstream.
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> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Tested-by: Matt Craighead <mcraighead@nvidia.com> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- net/sunrpc/xdr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index fddcccf..78ad0f6 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -233,10 +233,13 @@ _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); flush_dcache_page(*pgto); - kunmap_atomic(vfrom); kunmap_atomic(vto); } while ((len -= copy) != 0); -- 1.8.3.2
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