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[3.8.y.z,extended,stable] Patch "SUNRPC: Fix memory corruption issue on 32-bit highmem systems" has been added to staging queue

Message ID 1378414184-15531-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Sept. 5, 2013, 8:49 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    SUNRPC: Fix memory corruption issue on 32-bit highmem systems

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.9.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

From 55fd127db4884c86ab4b299c688962c798a0646c Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Wed, 28 Aug 2013 13:35:13 -0400
Subject: SUNRPC: Fix memory corruption issue on 32-bit highmem systems

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: Kamal Mostafa <kamal@canonical.com>
---
 net/sunrpc/xdr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--
1.8.1.2
diff mbox

Patch

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 5605563..ddbec19 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);
 		flush_dcache_page(*pgto);
-		kunmap_atomic(vfrom);
 		kunmap_atomic(vto);

 	} while ((len -= copy) != 0);