basic: util - fix errorhandling in unhexmem()

We were ignoring failures from unhexchar, which meant that invalid
hex characters were being turned into garbage rather than the string
rejected.

Fix this by making unhexmem return an error code, also change the API
slightly, to return the size of the returned memory, reflecting the
fact that the memory is a binary blob,and not a string.

For convenience, still append a trailing NULL byte to the returned
memory (not included in the returned size), allowing callers to
treat it as a string without doing a second copy.

1 files changed, 12 insertions, 8 deletions

diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c
index 322d57ddbb..735a775cb4 100644
--- a/src/libsystemd/sd-bus/bus-socket.c
+++ b/src/libsystemd/sd-bus/bus-socket.c
@@ -264,6 +264,8 @@ static bool line_begins(const char *s, size_t m, const char *word) {
 
 static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) {
         _cleanup_free_ char *token = NULL;
+        size_t len;
+        int r;
 
         if (!b->anonymous_auth)
                 return 0;
@@ -276,11 +278,12 @@ static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) {
 
         if (l % 2 != 0)
                 return 0;
-        token = unhexmem(p, l);
-        if (!token)
-                return -ENOMEM;
 
-        if (memchr(token, 0, l/2))
+        r = unhexmem(p, l, (void **) &token, &len);
+        if (r < 0)
+                return 0;
+
+        if (memchr(token, 0, len))
                 return 0;
 
         return !!utf8_is_valid(token);
@@ -288,6 +291,7 @@ static int verify_anonymous_token(sd_bus *b, const char *p, size_t l) {
 
 static int verify_external_token(sd_bus *b, const char *p, size_t l) {
         _cleanup_free_ char *token = NULL;
+        size_t len;
         uid_t u;
         int r;
 
@@ -307,11 +311,11 @@ static int verify_external_token(sd_bus *b, const char *p, size_t l) {
         if (l % 2 != 0)
                 return 0;
 
-        token = unhexmem(p, l);
-        if (!token)
-                return -ENOMEM;
+        r = unhexmem(p, l, (void**) &token, &len);
+        if (r < 0)
+                return 0;
 
-        if (memchr(token, 0, l/2))
+        if (memchr(token, 0, len))
                 return 0;
 
         r = parse_uid(token, &u);