From f93793fd73a629f4c86b0d91fd84fe175705aff9 Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@armlinux.org.uk>
Date: Mon, 9 Dec 2019 11:09:04 +0000
Subject: [PATCH] fs/adfs: map: fix map scanning
When scanning the map for a fragment id, we need to keep track of the
free space links, so we don't inadvertently believe that the freespace
link is a valid fragment id.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/adfs/map.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/fs/adfs/map.c b/fs/adfs/map.c
index 82e1bf101fe6..a81de80c45c1 100644
--- a/fs/adfs/map.c
+++ b/fs/adfs/map.c
@@ -72,9 +72,12 @@ static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
const u32 idmask = (1 << idlen) - 1;
unsigned char *map = dm->dm_bh->b_data;
unsigned int start = dm->dm_startbit;
- unsigned int fragend;
+ unsigned int freelink, fragend;
u32 frag;
+ frag = GET_FRAG_ID(map, 8, idmask & 0x7fff);
+ freelink = frag ? 8 + frag : 0;
+
do {
frag = GET_FRAG_ID(map, start, idmask);
@@ -82,7 +85,9 @@ static int lookup_zone(const struct adfs_discmap *dm, const unsigned int idlen,
if (fragend >= endbit)
goto error;
- if (frag == frag_id) {
+ if (start == freelink) {
+ freelink += frag & 0x7fff;
+ } else if (frag == frag_id) {
unsigned int length = fragend + 1 - start;
if (*offset < length)