From: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit ef17af2a817db97d42dd2ec0a425231748e23dbc upstream.
Bugs similar to the one in acbbe6fbb240 (kcmp: fix standard comparison
bug) are in rich supply.
In this variant, the problem is that struct xdr_netobj::len has type
unsigned int, so the expression o1->len - o2->len _also_ has type
unsigned int; it has completely well-defined semantics, and the result
is some non-negative integer, which is always representable in a long
long. But this means that if the conditional triggers, we are
guaranteed to return a positive value from compare_blob.
In this case it could be fixed by
- res = o1->len - o2->len;
+ res = (long long)o1->len - (long long)o2->len;
but I'd rather eliminate the usually broken 'return a - b;' idiom.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/nfsd/nfs4state.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 5ae1dd340073..0a138e4fc2e0 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1197,15 +1197,14 @@ static int copy_cred(struct svc_cred *target, struct svc_cred *source)
return 0;
}
-static long long
+static int
compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
{
- long long res;
-
- res = o1->len - o2->len;
- if (res)
- return res;
- return (long long)memcmp(o1->data, o2->data, o1->len);
+ if (o1->len < o2->len)
+ return -1;
+ if (o1->len > o2->len)
+ return 1;
+ return memcmp(o1->data, o2->data, o1->len);
}
static int same_name(const char *n1, const char *n2)
@@ -1389,7 +1388,7 @@ add_clp_to_name_tree(struct nfs4_client *new_clp, struct rb_root *root)
static struct nfs4_client *
find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
{
- long long cmp;
+ int cmp;
struct rb_node *node = root->rb_node;
struct nfs4_client *clp;
--
2.2.2
--
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