From: Chuck Lever <chuck.lever@oracle.com> stable inclusion from stable-v5.10.122 commit b585b87fd5c736522ee24b735ea893321f2cad49 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 6c254bf3b637dd4ef4f78eb78c7447419c0161d7 ] I found that NFSD's new NFSv3 READDIRPLUS XDR encoder was screwing up right at the end of the page array. xdr_get_next_encode_buffer() does not compute the value of xdr->end correctly: * The check to see if we're on the final available page in xdr->buf needs to account for the space consumed by @nbytes. * The new xdr->end value needs to account for the portion of @nbytes that is to be encoded into the previous buffer. Fixes: 2825a7f90753 ("nfsd4: allow encoding across page boundaries") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Reviewed-by: NeilBrown <neilb@suse.de> Reviewed-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- net/sunrpc/xdr.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 71e03b930b70..c8ed6d3d5762 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -752,7 +752,11 @@ static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr, */ xdr->p = (void *)p + frag2bytes; space_left = xdr->buf->buflen - xdr->buf->len; - xdr->end = (void *)p + min_t(int, space_left, PAGE_SIZE); + if (space_left - nbytes >= PAGE_SIZE) + xdr->end = (void *)p + PAGE_SIZE; + else + xdr->end = (void *)p + space_left - frag1bytes; + xdr->buf->page_len += frag2bytes; xdr->buf->len += nbytes; return p; -- 2.20.1