From a188ff405000902139a46d9e3753cae0e1168d46 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 10 Nov 2010 22:31:41 -0800 Subject: mtd-utils: nandwrite: prevent 32-bit overflow For large block- and page-sizes, the multiplication of ebsize_aligned and pagelen can overflow a 32-bit integer. This overflow can be prevented by a simple change in order of operations (i.e., do division first). Since ebsize_aligned is always a multiple of mtd.min_io_size, this produces no change in results. Signed-off-by: Brian Norris Acked-by: Mike Frysinger Signed-off-by: Artem Bityutskiy --- nandwrite.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/nandwrite.c b/nandwrite.c index 8ec5afe..aea7572 100644 --- a/nandwrite.c +++ b/nandwrite.c @@ -440,8 +440,13 @@ int main(int argc, char * const argv[]) goto closeall; } - // Allocate a buffer big enough to contain all the data (OOB included) for one eraseblock - filebuf_max = pagelen * ebsize_aligned / mtd.min_io_size; + /* + * Allocate a buffer big enough to contain all the data (OOB included) + * for one eraseblock. The order of operations here matters; if ebsize + * and pagelen are large enough, then "ebsize_aligned * pagelen" could + * overflow a 32-bit data type. + */ + filebuf_max = ebsize_aligned / mtd.min_io_size * pagelen; filebuf = xmalloc(filebuf_max); erase_buffer(filebuf, filebuf_max); -- cgit v1.2.3