apparmor: fix '*seclen' is never less than zero

smatch warnings:
security/apparmor/secid.c:162 apparmor_secid_to_secctx() warn: unsigned '*seclen' is never less than zero.

vim +162 security/apparmor/secid.c

140
141 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
142 {
143 /* TODO: cache secctx and ref count so we don't have to recreate */
144 struct aa_label *label = aa_secid_to_label(secid);
145
146 AA_BUG(!secdata);
147 AA_BUG(!seclen);
148
149 if (!label)
150 return -EINVAL;
151
152 if (secdata)
153 *seclen = aa_label_asxprint(secdata, root_ns, label,
154 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
155 FLAG_HIDDEN_UNCONFINED |
156 FLAG_ABS_ROOT, GFP_ATOMIC);
157 else
158 *seclen = aa_label_snxprint(NULL, 0, root_ns, label,
159 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
160 FLAG_HIDDEN_UNCONFINED |
161 FLAG_ABS_ROOT);
> 162 if (*seclen < 0)
163 return -ENOMEM;
164
165 return 0;
166 }
167

Fixes: c092921219d2 ("apparmor: add support for mapping secids and using secctxes")
Signed-off-by: John Johansen <[e-mail]>

security/apparmor/secid.c

···
 {
 	/* TODO: cache secctx and ref count so we don't have to recreate */
 	struct aa_label *label = aa_secid_to_label(secid);
+	int len;
 
 	AA_BUG(!secdata);
 	AA_BUG(!seclen);
···
 		return -EINVAL;
 
 	if (secdata)
-		*seclen = aa_label_asxprint(secdata, root_ns, label,
-					    FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
-					    FLAG_HIDDEN_UNCONFINED |
-					    FLAG_ABS_ROOT, GFP_ATOMIC);
+		len = aa_label_asxprint(secdata, root_ns, label,
+					FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
+					FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT,
+					GFP_ATOMIC);
 	else
-		*seclen = aa_label_snxprint(NULL, 0, root_ns, label,
-					    FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
-					    FLAG_HIDDEN_UNCONFINED |
-					    FLAG_ABS_ROOT);
-	if (*seclen < 0)
+		len = aa_label_snxprint(NULL, 0, root_ns, label,
+					FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
+					FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT);
+	if (len < 0)
 		return -ENOMEM;
+
+	*seclen = len;
 
 	return 0;
 }