fat: handle paths that include ../

[karo-tx-uboot.git] / fs / fat / fat.c

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index bccc3e3ed8fd0929c7f1adf33b2125178be75ccb..a863644d648068749a5803276d82ed5feca17604 100644 (file)
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -895,6 +895,7 @@ int do_fat_read_at(const char *filename, loff_t pos, void *buffer,
        strcpy(fnamecopy, filename);
        downcase(fnamecopy);
 
+root_reparse:
        if (*fnamecopy == '\0') {
                if (!dols)
                        goto exit;
@@ -1180,6 +1181,34 @@ rootdir_done:
                if (isdir && !(dentptr->attr & ATTR_DIR))
                        goto exit;
 
+               /*
+                * If we are looking for a directory, and found a directory
+                * type entry, and the entry is for the root directory (as
+                * denoted by a cluster number of 0), jump back to the start
+                * of the function, since at least on FAT12/16, the root dir
+                * lives in a hard-coded location and needs special handling
+                * to parse, rather than simply following the cluster linked
+                * list in the FAT, like other directories.
+                */
+               if (isdir && (dentptr->attr & ATTR_DIR) && !START(dentptr)) {
+                       /*
+                        * Modify the filename to remove the prefix that gets
+                        * back to the root directory, so the initial root dir
+                        * parsing code can continue from where we are without
+                        * confusion.
+                        */
+                       strcpy(fnamecopy, nextname ?: "");
+                       /*
+                        * Set up state the same way as the function does when
+                        * first started. This is required for the root dir
+                        * parsing code operates in its expected environment.
+                        */
+                       subname = "";
+                       cursect = mydata->rootdir_sect;
+                       isdir = 0;
+                       goto root_reparse;
+               }
+
                if (idx >= 0)
                        subname = nextname;
        }