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From: Chuck Lever <chuck.lever@oracle.com>
To: linux-nfs@vger.kernel.org
Subject: [PATCH v3 3/6] NFSD: Protect against send buffer overflow in NFSv2 READDIR
Date: Thu, 01 Sep 2022 15:10:05 -0400	[thread overview]
Message-ID: <166205940565.1435.7170548905174362083.stgit@manet.1015granger.net> (raw)
In-Reply-To: <166204973526.1435.6068003336048840051.stgit@manet.1015granger.net>

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>
---
 fs/nfsd/nfsproc.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index 7381972f1677..ddb1902c0a18 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++;
 



  parent reply	other threads:[~2022-09-01 19:10 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-01 19:09 [PATCH v3 0/6] Fixes for server-side xdr_stream overhaul Chuck Lever
2022-09-01 19:09 ` [PATCH v3 1/6] SUNRPC: Fix svcxdr_init_decode's end-of-buffer calculation Chuck Lever
2022-09-01 19:09 ` [PATCH v3 2/6] SUNRPC: Fix svcxdr_init_encode's buflen calculation Chuck Lever
2022-09-01 19:10 ` Chuck Lever [this message]
2022-09-02 13:09   ` [PATCH v3 3/6] NFSD: Protect against send buffer overflow in NFSv2 READDIR Jeff Layton
2022-09-01 19:10 ` [PATCH v3 4/6] NFSD: Protect against send buffer overflow in NFSv3 READDIR Chuck Lever
2022-09-02 13:12   ` Jeff Layton
2022-09-01 19:10 ` [PATCH v3 5/6] NFSD: Protect against send buffer overflow in NFSv2 READ Chuck Lever
2022-09-02 13:14   ` Jeff Layton
2022-09-01 19:10 ` [PATCH v3 6/6] NFSD: Protect against send buffer overflow in NFSv3 READ Chuck Lever
2022-09-02 13:15   ` Jeff Layton

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