From e26c12c777118d65aeb97eb1651338e7decae80e Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Wed, 15 Apr 2015 16:17:05 -0700 Subject: [PATCH] lib/vsprintf.c: reduce stack use in number() At least since the initial git commit, when base was passed as a separate parameter, number() has only been called with bases 8, 10 and 16. I'm guessing that 66 was to accommodate 64 0/1, a sign and a '\0', but the buffer is only used for the actual digits. Octal digits carry 3 bits of information, so 24 is enough. Spell that 3*sizeof(num) so one less place needs to be changed should long long ever be 128 bits. Also remove the commented-out code that would handle an arbitrary base. Signed-off-by: Rasmus Villemoes Cc: Peter Zijlstra Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/vsprintf.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 318d583fe862..98f1ce907d3d 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -386,7 +386,7 @@ char *number(char *buf, char *end, unsigned long long num, /* we are called with base 8, 10 or 16, only, thus don't need "G..." */ static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */ - char tmp[66]; + char tmp[3 * sizeof(num)]; char sign; char locase; int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10); @@ -423,11 +423,6 @@ char *number(char *buf, char *end, unsigned long long num, i = 0; if (num < spec.base) tmp[i++] = digits[num] | locase; - /* Generic code, for any base: - else do { - tmp[i++] = (digits[do_div(num,base)] | locase); - } while (num != 0); - */ else if (spec.base != 10) { /* 8 or 16 */ int mask = spec.base - 1; int shift = 3;