2012-11-16 21:31:23

by Jim Rees

Subject: [PATCH] NFS: Reduce stack use in encode_exchange_id()

encode_exchange_id() uses more stack space than necessary, giving a compile
time warning. Reduce the size of the static buffer for implementation name.

Signed-off-by: Jim Rees <[email protected]>
Reviewed-by: "Adamson, Dros" <[email protected]>
---
fs/nfs/nfs4xdr.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 672d9b0..e9c101d 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1706,12 +1706,15 @@ static void encode_bind_conn_to_session(struct xdr_stream *xdr,
*p = 0; /* use_conn_in_rdma_mode = False */
}

+#define IMPL_NAME_LIMIT (sizeof(utsname()->sysname) + sizeof(utsname()->release) + \
+ sizeof(utsname()->version) + sizeof(utsname()->machine) + 8)
+
static void encode_exchange_id(struct xdr_stream *xdr,
struct nfs41_exchange_id_args *args,
struct compound_hdr *hdr)
{
__be32 *p;
- char impl_name[NFS4_OPAQUE_LIMIT];
+ char impl_name[IMPL_NAME_LIMIT];
int len = 0;

encode_op_hdr(xdr, OP_EXCHANGE_ID, decode_exchange_id_maxsz, hdr);
@@ -1726,7 +1729,7 @@ static void encode_exchange_id(struct xdr_stream *xdr,
if (send_implementation_id &&
sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN) > 1 &&
sizeof(CONFIG_NFS_V4_1_IMPLEMENTATION_ID_DOMAIN)
- <= NFS4_OPAQUE_LIMIT + 1)
+ <= sizeof(impl_name) + 1)
len = snprintf(impl_name, sizeof(impl_name), "%s %s %s %s",
utsname()->sysname, utsname()->release,
utsname()->version, utsname()->machine);
--
1.7.9.5

2012-11-16 21:59:21

by Myklebust, Trond

Subject: Re: [PATCH] NFS: Reduce stack use in encode_exchange_id()

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2012-11-16 22:25:28

by Jim Rees

Subject: Re: [PATCH] NFS: Reduce stack use in encode_exchange_id()

Myklebust, Trond wrote:

Hmm... Shouldn't we also be changing encode_exchange_id_maxsz to mirror
this new buffer limit?

Probably. I'll fix it. Thanks.