This is a note to let you know that I've just added the patch titled
SUNRPC: Fix svcxdr_init_encode's buflen calculation
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sunrpc-fix-svcxdr_init_encode-s-buflen-calculation.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c001d6331baa0bef0d35e79301df8053e62743cb
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu Sep 1 15:09:59 2022 -0400
SUNRPC: Fix svcxdr_init_encode's buflen calculation
[ Upstream commit 1242a87da0d8cd2a428e96ca68e7ea899b0f4624 ]
Commit 2825a7f90753 ("nfsd4: allow encoding across page boundaries")
added an explicit computation of the remaining length in the rq_res
XDR buffer.
The computation appears to suffer from an "off-by-one" bug. Because
buflen is too large by one page, XDR encoding can run off the end of
the send buffer by eventually trying to use the struct page address
in rq_page_end, which always contains NULL.
Fixes: bddfdbcddbe2 ("NFSD: Extract the svcxdr_init_encode() helper")
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 6be55d0e73fd..045f34add206 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -609,7 +609,7 @@ static inline void svcxdr_init_encode(struct svc_rqst *rqstp)
xdr->end = resv->iov_base + PAGE_SIZE - rqstp->rq_auth_slack;
buf->len = resv->iov_len;
xdr->page_ptr = buf->pages - 1;
- buf->buflen = PAGE_SIZE * (1 + rqstp->rq_page_end - buf->pages);
+ buf->buflen = PAGE_SIZE * (rqstp->rq_page_end - buf->pages);
buf->buflen -= rqstp->rq_auth_slack;
xdr->rqst = NULL;
}
