Re: [PATCH] genalloc: fix overflow of ending address of memory chunk

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 07 Aug 2013 14:26:18 +0900 Joonyoung Shim <jy0922.shim@samsung.com> wrote:

> In struct gen_pool_chunk, end_addr means ending address of memory chunk,
> but actually it is starting address + size of memory chunk in codes, so
> it points the address increased one instead of correct ending address.
> 
> The ending address of memory chunk increased one will cause overflow on
> the case to use memory chunk including last address of memory map, e.g.
> when starting address is 0xFFF00000 and size is 0x100000 on 32bit
> machine, ending address will be 0x100000000.
> 
> Use correct ending address like starting address + size - 1.

This might help:

From: Andrew Morton <akpm@linux-foundation.org>
Subject: genalloc-fix-overflow-of-ending-address-of-memory-chunk-fix

add comment to struct gen_pool_chunk:end_addr

Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/genalloc.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN lib/genalloc.c~genalloc-fix-overflow-of-ending-address-of-memory-chunk-fix lib/genalloc.c
diff -puN include/linux/genalloc.h~genalloc-fix-overflow-of-ending-address-of-memory-chunk-fix include/linux/genalloc.h
--- a/include/linux/genalloc.h~genalloc-fix-overflow-of-ending-address-of-memory-chunk-fix
+++ a/include/linux/genalloc.h
@@ -66,8 +66,8 @@ struct gen_pool_chunk {
 	struct list_head next_chunk;	/* next chunk in pool */
 	atomic_t avail;
 	phys_addr_t phys_addr;		/* physical starting address of memory chunk */
-	unsigned long start_addr;	/* starting address of memory chunk */
-	unsigned long end_addr;		/* ending address of memory chunk */
+	unsigned long start_addr;	/* start address of memory chunk */
+	unsigned long end_addr;		/* end address of memory chunk (inclusive) */
 	unsigned long bits[0];		/* bitmap for allocating memory chunk */
 };
 
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