FAT: buffer overflow with FAT12/16

Last commit 3831530dcb7b71329c272ccd6181f8038b6a6dd0a was intended
"explicitly specify FAT12/16 root directory parsing buffer size, instead
of relying on cluster size". Howver, the underlying function requires
the size of the buffer in blocks, not in bytes, and instead of passing
a double sector size a request for 1024 blocks is sent. This generates
a buffer overflow with overwriting of other structure (in the case seen,
USB structures were overwritten).

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Mikhail Zolotaryov <lebon@lebon.org.ua>

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 744e961..a75e4f2 100644 (file)
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -858,7 +858,7 @@ do_fat_read (const char *filename, void *buffer, unsigned long maxsize,
                if (disk_read(cursect,
                                (mydata->fatsize == 32) ?
                                (mydata->clust_size) :
-                               LINEAR_PREFETCH_SIZE,
+                               LINEAR_PREFETCH_SIZE / SECTOR_SIZE,
                                do_fat_read_block) < 0) {
                        debug("Error: reading rootdir block\n");
                        return -1;