From: Rasmus Villemoes <linux@rasmusvillemoes.dk> Date: Fri, 5 Dec 2014 15:40:07 +0000 (+0100) Subject: fs: nfsd: Fix signedness bug in compare_blob X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=ef17af2a817db97d42dd2ec0a425231748e23dbc;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git fs: nfsd: Fix signedness bug in compare_blob 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@primarydata.com> Cc: <stable@vger.kernel.org> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: J. Bruce Fields <bfields@redhat.com> --- diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 1379d86f7b4f..8770ba75b7b4 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1714,15 +1714,14 @@ 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) @@ -1910,7 +1909,7 @@ 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;