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authorJ. Bruce Fields <bfields@redhat.com>2014-12-22 16:14:51 -0500
committerJ. Bruce Fields <bfields@redhat.com>2015-01-07 14:03:58 -0500
commit49a068f82a1d30eb585d7804b05948376be6cf9a (patch)
tree670d3bc2de3e9faec18f6fbc36f0a997f99a0992
parent94ae1db226a5bcbb48372d81161f084c9e283fd8 (diff)
downloadop-kernel-dev-49a068f82a1d30eb585d7804b05948376be6cf9a.zip
op-kernel-dev-49a068f82a1d30eb585d7804b05948376be6cf9a.tar.gz
rpc: fix xdr_truncate_encode to handle buffer ending on page boundary
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" Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>
-rw-r--r--net/sunrpc/xdr.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 1cb6124..4439ac4 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -606,7 +606,7 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
struct kvec *head = buf->head;
struct kvec *tail = buf->tail;
int fraglen;
- int new, old;
+ int new;
if (len > buf->len) {
WARN_ON_ONCE(1);
@@ -629,8 +629,8 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
buf->len -= fraglen;
new = buf->page_base + buf->page_len;
- old = new + fraglen;
- xdr->page_ptr -= (old >> PAGE_SHIFT) - (new >> PAGE_SHIFT);
+
+ xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
if (buf->page_len) {
xdr->p = page_address(*xdr->page_ptr);
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