sparc32: Fixed unaligned memory copying in function __csum_partial_copy_sparc_generic

When we are in the label cc_dword_align, registers %o0 and %o1 have the same last 2 bits,
but it's not guaranteed one of them is zero. So we can get unaligned memory access
in label ccte. Example of parameters which lead to this:
%o0=0x7ff183e9, %o1=0x8e709e7d, %g1=3

With the parameters I had a memory corruption, when the additional 5 bytes were rewritten.
This patch corrects the error.

One comment to the patch. We don't care about the third bit in %o1, because cc_end_cruft
stores word or less.

Signed-off-by: Tkhai Kirill <tkhai@yandex.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/arch/sparc/lib/checksum_32.S b/arch/sparc/lib/checksum_32.S
index 3632cb34e914..0084c3361e15 100644
--- a/arch/sparc/lib/checksum_32.S
+++ b/arch/sparc/lib/checksum_32.S
@@ -289,10 +289,16 @@ cc_end_cruft:
 
         /* Also, handle the alignment code out of band. */
 cc_dword_align:
-        cmp     %g1, 6
-        bl,a    ccte
+        cmp     %g1, 16
+        bge     1f
+         srl    %g1, 1, %o3
+2:      cmp     %o3, 0
+        be,a    ccte
          andcc  %g1, 0xf, %o3
-        andcc   %o0, 0x1, %g0
+        andcc   %o3, %o0, %g0   ! Check %o0 only (%o1 has the same last 2 bits)
+        be,a    2b
+         srl    %o3, 1, %o3
+1:      andcc   %o0, 0x1, %g0
         bne     ccslow
          andcc  %o0, 0x2, %g0
         be      1f