2012-11-16 23:12:11

by Jim Rees

Subject: [PATCH v2] 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 | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 672d9b0..cc2f8a9 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -270,6 +270,8 @@ static int nfs4_stat_to_errno(int);

#if defined(CONFIG_NFS_V4_1)
#define NFS4_MAX_MACHINE_NAME_LEN (64)
+#define IMPL_NAME_LIMIT (sizeof(utsname()->sysname) + sizeof(utsname()->release) + \
+ sizeof(utsname()->version) + sizeof(utsname()->machine) + 8)

#define encode_exchange_id_maxsz (op_encode_hdr_maxsz + \
encode_verifier_maxsz + \
@@ -282,7 +284,7 @@ static int nfs4_stat_to_errno(int);
1 /* nii_domain */ + \
XDR_QUADLEN(NFS4_OPAQUE_LIMIT) + \
1 /* nii_name */ + \
- XDR_QUADLEN(NFS4_OPAQUE_LIMIT) + \
+ XDR_QUADLEN(IMPL_NAME_LIMIT) + \
3 /* nii_date */)
#define decode_exchange_id_maxsz (op_decode_hdr_maxsz + \
2 /* eir_clientid */ + \
@@ -1711,7 +1713,7 @@ static void encode_exchange_id(struct xdr_stream *xdr,
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 +1728,7 @@ 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

2012-11-17 00:53:09

by Myklebust, Trond

Subject: Re: [PATCH v2] NFS: Reduce stack use in encode_exchange_id()

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