[syslinux:master] Correct initialization of the cache doubly-linked list

[syslinux-bot for H. Peter Anvin]

Commit-ID:  0a0e0e41cad93cd16c323cf16f40264a21eedd6c
Gitweb:     http://www.syslinux.org/commit/0a0e0e41cad93cd16c323cf16f40264a21eedd6c
Author:     H. Peter Anvin <hpa at zytor.com>
AuthorDate: Thu, 19 Jul 2012 07:29:55 -0700
Committer:  H. Peter Anvin <hpa at zytor.com>
CommitDate: Thu, 19 Jul 2012 07:29:55 -0700

Correct initialization of the cache doubly-linked list

The initialization of the cache doubly-linked list had
head->next->prev instead of head->prev->next; this entry is supposed
to initialize the ->next entry of the last entry in the list (which
points back to the head node.)

For clarity, consistently use "head" to refer to the head node; the
mixing of "head" and "dev->cache_head" needlessly obfuscated the code.

The wild pointer reference caused crashes on some systems.

Reported-by: Jan Safrata <jsafrata at centrum.cz>
Signed-off-by: H. Peter Anvin <hpa at zytor.com>

---
 core/fs/cache.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/core/fs/cache.c b/core/fs/cache.c
index 0d7891b..3b21fc2 100644
--- a/core/fs/cache.c
+++ b/core/fs/cache.c
@@ -37,10 +37,10 @@ void cache_init(struct device *dev, int block_size_shift)
 
     dev->cache_head = head = (struct cache *)
 	(data + (dev->cache_entries << block_size_shift));
-    cache = dev->cache_head + 1; /* First cache descriptor */
+    cache = head + 1;		/* First cache descriptor */
 
     head->prev  = &cache[dev->cache_entries-1];
-    head->next->prev = dev->cache_head;
+    head->prev->next = head;
     head->block = -1;
     head->data  = NULL;