From: Brian Norris Date: Thu, 11 Nov 2010 06:31:41 +0000 (-0800) Subject: mtd-utils: nandwrite: prevent 32-bit overflow X-Git-Tag: v1.4.2~13 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a188ff405000902139a46d9e3753cae0e1168d46;p=mtd-utils.git 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 --- 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);