Eric Lee / smarc-ti-linux-kernel

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Commit 9e80aeb7c7244c29b2c28049cd2149d3ab10a56a

Authored by J. Bruce Fields
Committed by Greg Kroah-Hartman
1 parent 713beaa02f

rpc: fix xdr_truncate_encode to handle buffer ending on page boundary 

commit 49a068f82a1d30eb585d7804b05948376be6cf9a upstream.

A struct xdr_stream at a page boundary might point to the end of one
page or the beginning of the next, but xdr_truncate_encode isn't
prepared to handle the former.

This can cause corruption of NFSv4 READDIR replies in the case that a
readdir entry that would have exceeded the client's dircount/maxcount
limit would have ended exactly on a 4k page boundary.  You're more
likely to hit this case on large directories.

Other xdr_truncate_encode callers are probably also affected.

Reported-by: Holger Hoffstätte <holger.hoffstaette@googlemail.com>
Tested-by: Holger Hoffstätte <holger.hoffstaette@googlemail.com>
Fixes: 3e19ce762b53 "rpc: xdr_truncate_encode"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 3 additions and 3 deletions Side-by-side Diff

... ... @@ -606,7 +606,7 @@
606 606 struct kvec *head = buf->head;
607 607 struct kvec *tail = buf->tail;
608 608 int fraglen;
609   - int new, old;
  609 + int new;
610 610  
611 611 if (len > buf->len) {
612 612 WARN_ON_ONCE(1);
... ... @@ -628,8 +628,8 @@
628 628 buf->len -= fraglen;
629 629  
630 630 new = buf->page_base + buf->page_len;
631   - old = new + fraglen;
632   - xdr->page_ptr -= (old >> PAGE_SHIFT) - (new >> PAGE_SHIFT);
  631 +
  632 + xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
633 633  
634 634 if (buf->page_len && buf->len == len) {
635 635 xdr->p = page_address(*xdr->page_ptr);