path-util: tighten path_is_valid() checks

This tightens the path_is_valid() checking: it now tests whether each
component in the path is bound by FILENAME_MAX in its size.

1 files changed, 19 insertions, 4 deletions

diff --git a/src/basic/path-util.c b/src/basic/path-util.c
index 3dff09b151..f7498d0125 100644
--- a/src/basic/path-util.c
+++ b/src/basic/path-util.c
@@ -891,7 +891,7 @@ bool filename_is_valid(const char *p) {
         if (*e != 0)
                 return false;
 
-        if (e - p > FILENAME_MAX) /* FILENAME_MAX is counted *without* the trailing NUL byte */
+        if (e - p > NAME_MAX) /* NAME_MAX is counted *without* the trailing NUL byte */
                 return false;
 
         return true;
@@ -902,10 +902,25 @@ bool path_is_valid(const char *p) {
         if (isempty(p))
                 return false;
 
-        if (strlen(p) >= PATH_MAX) /* PATH_MAX is counted *with* the trailing NUL byte */
-                return false;
+        for (const char *e = p;;) {
+                size_t n;
 
-        return true;
+                /* Skip over slashes */
+                e += strspn(e, "/");
+                if (e - p >= PATH_MAX) /* Already reached the maximum length for a path? (PATH_MAX is counted
+                                        * *with* the trailing NUL byte) */
+                        return false;
+                if (*e == 0)           /* End of string? Yay! */
+                        return true;
+
+                /* Skip over one component */
+                n = strcspn(e, "/");
+                if (n > NAME_MAX)      /* One component larger than NAME_MAX? (NAME_MAX is counted *without* the
+                                        * trailing NUL byte) */
+                        return false;
+
+                e += n;
+        }
 }
 
 bool path_is_normalized(const char *p) {