From 0dc1bfb7302d220a48364263d5632d6d572b069b Mon Sep 17 00:00:00 2001
From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Mon, 2 Jul 2018 02:41:23 +0200
Subject: [PATCH] fs: fat: cannot write to subdirectories
fs_fat_write() is not able to write to subdirectories.
Currently if a filepath with a leading slash is passed, the slash is
treated as part of the filename to be created in the root directory.
Strip leading (back-)slashes.
Check that the remaining filename does not contain any illegal characters
(<>:"/\|?*). This way we will throw an error when trying to write to a
subdirectory.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
fs/fat/fat_write.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 3b77557b3e..27e0ff6696 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -909,9 +909,11 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
volume_info volinfo;
fsdata datablock;
fsdata *mydata = &datablock;
- int cursect;
+ int cursect, i;
int ret = -1, name_len;
char l_filename[VFAT_MAXLEN_BYTES];
+ char bad[2] = " ";
+ const char illegal[] = "<>:\"/\\|?*";
*actwrite = size;
dir_curclust = 0;
@@ -971,6 +973,18 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size,
}
dentptr = (dir_entry *) do_fat_read_at_block;
+ /* Strip leading (back-)slashes */
+ while ISDIRDELIM(*filename)
+ ++filename;
+ /* Check that the filename is valid */
+ for (i = 0; i < strlen(illegal); ++i) {
+ *bad = illegal[i];
+ if (strstr(filename, bad)) {
+ printf("FAT: illegal filename (%s)\n", filename);
+ return -1;
+ }
+ }
+
name_len = strlen(filename);
if (name_len >= VFAT_MAXLEN_BYTES)
name_len = VFAT_MAXLEN_BYTES - 1;
--
2.39.5