diff mbox series

[v3,3/6] NFSD: Protect against send buffer overflow in NFSv2 READDIR

Message ID 166205940565.1435.7170548905174362083.stgit@manet.1015granger.net (mailing list archive)
State New, archived
Headers show
Series Fixes for server-side xdr_stream overhaul | expand

Commit Message

Chuck Lever Sept. 1, 2022, 7:10 p.m. UTC 
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(-)

Comments

Jeffrey Layton Sept. 2, 2022, 1:09 p.m. UTC | #1 
On Thu, 2022-09-01 at 15:10 -0400, Chuck Lever wrote:
> 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++;
>  
> 
> 

Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff mbox series

Patch

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++;