tree 6e0e2e2b91cc4a9464d3a9b2ebd407303383fe85
parent 42e4e7f271f94b486d5f373036e5d2d47850d102
author Trond Myklebust <Trond.Myklebust@netapp.com> 1377711313 -0400
committer chrmhoffmann <chrmhoffmann@gmail.com> 1586074726 +0200

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>