2024-01-25 15:07:10

by Jorge Mora

Subject: [PATCH] NFSD: fix LISTXATTRS returning more bytes than maxcount

The maxcount is the maximum number of bytes for the LISTXATTRS4resok
result. This includes the cookie and the count for the name array,
thus subtract 12 bytes from the maxcount: 8 (cookie) + 4 (array count)
when filling up the name array.

Fixes: 23e50fe3a5e6 ("nfsd: implement the xattr functions and en/decode logic")
Signed-off-by: Jorge Mora <[email protected]>
---
fs/nfsd/nfs4xdr.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 92c7dde148a4..17e6404f4296 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -5168,7 +5168,8 @@ nfsd4_encode_listxattrs(struct nfsd4_compoundres *resp, __be32 nfserr,
sp = listxattrs->lsxa_buf;
nuser = 0;

- xdrleft = listxattrs->lsxa_maxcount;
+ /* Bytes left is maxcount - 8 (cookie) - 4 (array count) */
+ xdrleft = listxattrs->lsxa_maxcount - 12;

while (left > 0 && xdrleft > 0) {
slen = strlen(sp);
--
2.43.0

2024-01-25 17:11:55

by Jeffrey Layton

Subject: Re: [PATCH] NFSD: fix LISTXATTRS returning more bytes than maxcount

On Thu, 2024-01-25 at 07:42 -0700, Jorge Mora wrote:
> The maxcount is the maximum number of bytes for the LISTXATTRS4resok
> result. This includes the cookie and the count for the name array,
> thus subtract 12 bytes from the maxcount: 8 (cookie) + 4 (array count)
> when filling up the name array.
>
> Fixes: 23e50fe3a5e6 ("nfsd: implement the xattr functions and en/decode logic")
> Signed-off-by: Jorge Mora <[email protected]>
> ---
> fs/nfsd/nfs4xdr.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 92c7dde148a4..17e6404f4296 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -5168,7 +5168,8 @@ nfsd4_encode_listxattrs(struct nfsd4_compoundres *resp, __be32 nfserr,
> sp = listxattrs->lsxa_buf;
> nuser = 0;
>
> - xdrleft = listxattrs->lsxa_maxcount;
> + /* Bytes left is maxcount - 8 (cookie) - 4 (array count) */
> + xdrleft = listxattrs->lsxa_maxcount - 12;
>
> while (left > 0 && xdrleft > 0) {
> slen = strlen(sp);

Nice catch!

Reviewed-by: Jeff Layton <[email protected]>

2024-01-25 18:03:30

by Chuck Lever

Subject: Re: [PATCH] NFSD: fix LISTXATTRS returning more bytes than maxcount

On Thu, Jan 25, 2024 at 07:42:23AM -0700, Jorge Mora wrote:
> The maxcount is the maximum number of bytes for the LISTXATTRS4resok
> result. This includes the cookie and the count for the name array,
> thus subtract 12 bytes from the maxcount: 8 (cookie) + 4 (array count)
> when filling up the name array.
>
> Fixes: 23e50fe3a5e6 ("nfsd: implement the xattr functions and en/decode logic")
> Signed-off-by: Jorge Mora <[email protected]>
> ---
> fs/nfsd/nfs4xdr.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index 92c7dde148a4..17e6404f4296 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -5168,7 +5168,8 @@ nfsd4_encode_listxattrs(struct nfsd4_compoundres *resp, __be32 nfserr,
> sp = listxattrs->lsxa_buf;
> nuser = 0;
>
> - xdrleft = listxattrs->lsxa_maxcount;
> + /* Bytes left is maxcount - 8 (cookie) - 4 (array count) */
> + xdrleft = listxattrs->lsxa_maxcount - 12;
>
> while (left > 0 && xdrleft > 0) {
> slen = strlen(sp);
> --
> 2.43.0
>

All four applied to nfsd-next.

Note this checkpatch complaint:

WARNING: From:/Signed-off-by: email address mismatch:
'From: Jorge Mora <[email protected]>' != 'Signed-off-by: Jorge Mora <[email protected]>'

I'm not sure whether that mismatch is a critical problem. These
look like good fixes and b4 says your DKIM is good, so I applied
them anyway.

--
Chuck Lever