fs: nfsd: Fix signedness bug in compare_blob
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@primarydata.com> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -1200,15 +1200,14 @@ static int copy_cred(struct svc_cred *target, struct svc_cred *source)
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return 0;
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return 0;
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}
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}
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static long long
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static int
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compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
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compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
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{
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{
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long long res;
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if (o1->len < o2->len)
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return -1;
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res = o1->len - o2->len;
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if (o1->len > o2->len)
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if (res)
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return 1;
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return res;
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return memcmp(o1->data, o2->data, o1->len);
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return (long long)memcmp(o1->data, o2->data, o1->len);
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}
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}
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static int same_name(const char *n1, const char *n2)
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static int same_name(const char *n1, const char *n2)
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@ -1365,7 +1364,7 @@ add_clp_to_name_tree(struct nfs4_client *new_clp, struct rb_root *root)
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static struct nfs4_client *
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static struct nfs4_client *
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find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
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find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
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{
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{
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long long cmp;
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int cmp;
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struct rb_node *node = root->rb_node;
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struct rb_node *node = root->rb_node;
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struct nfs4_client *clp;
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struct nfs4_client *clp;
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