diff mbox series

[6.0,224/862] NFSD: Protect against send buffer overflow in NFSv2 READDIR

Message ID 20221019083259.940007979@linuxfoundation.org
State New
Headers
Series None |

Commit Message

Greg KH Oct. 19, 2022, 8:25 a.m. UTC 
  From: Chuck Lever <chuck.lever@oracle.com>

[ 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@oracle.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/nfsd/nfsproc.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index fcbf7e4083af..4b19cc727ea5 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -568,12 +568,11 @@  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++;