[U-Boot] [PATCH v4 1/2] dlmalloc: fix malloc range at end of ram

[Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>]

If the malloc range passed to mem_malloc_init() is at the end of address
range and 'start + size' overflows to 0, following allocations fail as
mem_malloc_end is zero (which looks like uninitialized).

Fix this by subtracting 1 of 'start + size' overflows to zero.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
---

Changes in v4: None
Changes in v3: None

 common/dlmalloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index edaad299bb..51d3bd671a 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -603,6 +603,10 @@ void mem_malloc_init(ulong start, ulong size)
 	mem_malloc_start = start;
 	mem_malloc_end = start + size;
 	mem_malloc_brk = start;
+	if (start && size && !mem_malloc_end) {
+		/* overflow: malloc area is at end of address range */
+		mem_malloc_end--;
+	}
 
 	debug("using memory %#lx-%#lx for malloc()\n", mem_malloc_start,
 	      mem_malloc_end);
-- 
2.17.1