From: nbd <nbd@3c298f89-4303-0410-b956-a3cf2f4a3e73>
Date: Sun, 18 Feb 2007 13:52:14 +0000 (+0000)
Subject: Finally fix the pesky x86-2.6 block2mtd related crash (#1058)
X-Git-Url: https://git.archive.openwrt.org/?p=openwrt.git;a=commitdiff_plain;h=a7cb17cea9375f522cb87b2d53808e1cfaa713c1

Finally fix the pesky x86-2.6 block2mtd related crash (#1058)
When erasing blocks, block2mtd checks the block on the physical disk
to see if everything's filled with 0xff. When grabbing a page from the page
cache, it initializes the limit as <start address> + PAGE_SIZE.
Turns out that the pointer to the status page is (unsigned long *), and
thus it adds (PAGE_SIZE * 4).
This would never have been caught, if it wasn't for the unlikely event
that block2mtd catches the *last* page available in the system ram and
thus tries to scan 4 memory pages from there.
The absolutely trivial fix is to do a double cast (cast to (u8 *), add
PAGE_SIZE, then cast to (unsigned long *))

... and there was much rejoicing


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@6318 3c298f89-4303-0410-b956-a3cf2f4a3e73
---

diff --git a/target/linux/generic-2.6/patches/212-block2mtd_erase_scan.patch b/target/linux/generic-2.6/patches/212-block2mtd_erase_scan.patch
new file mode 100644
index 0000000000..76b4f5d4c9
--- /dev/null
+++ b/target/linux/generic-2.6/patches/212-block2mtd_erase_scan.patch
@@ -0,0 +1,11 @@
+--- linux.dev/drivers/mtd/devices/block2mtd.c.old	2007-02-18 14:08:59.519952312 +0100
++++ linux.dev/drivers/mtd/devices/block2mtd.c	2007-02-18 14:09:04.219237912 +0100
+@@ -111,7 +111,7 @@
+ 		if (IS_ERR(page))
+ 			return PTR_ERR(page);
+ 
+-		max = (u_long*)page_address(page) + PAGE_SIZE;
++		max = (u_long*) ((u8 *) page_address(page) + PAGE_SIZE);
+ 		for (p=(u_long*)page_address(page); p<max; p++)
+ 			if (*p != -1UL) {
+ 				lock_page(page);