This is a note to let you know that I've just added the patch titled
NFSD: Protect against send buffer overflow in NFSv2 READDIR
to the 5.10-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:
nfsd-protect-against-send-buffer-overflow-in-nfsv2-r.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2fa75cb1316a35dee8db48f5b5265d6f69d66663
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Thu Sep 1 15:10:05 2022 -0400
NFSD: Protect against send buffer overflow in NFSv2 READDIR
[ Upstream commit 00b4492686e0497fdb924a9d4c8f6f99377e176c ]
Restore the previous limit on the @count argument to prevent a
buffer overflow attack.
Fixes: 53b1119a6e50 ("NFSD: Fix READDIR buffer overflow")
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index e533550a26db5..559603a0a5358 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -567,12 +567,11 @@ static void nfsd_init_dirlist_pages(struct svc_rqst *rqstp,
struct xdr_buf *buf = &resp->dirlist;
struct xdr_stream *xdr = &resp->xdr;
- count = clamp(count, (u32)(XDR_UNIT * 2), svc_max_payload(rqstp));
-
memset(buf, 0, sizeof(*buf));
/* Reserve room for the NULL ptr & eof flag (-2 words) */
- buf->buflen = count - XDR_UNIT * 2;
+ buf->buflen = clamp(count, (u32)(XDR_UNIT * 2), (u32)PAGE_SIZE);
+ buf->buflen -= XDR_UNIT * 2;
buf->pages = rqstp->rq_next_page;
rqstp->rq_next_page++;
