From: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx> Previously, we used __builtin_mul_overflow() to check for overflow in the multiplication operation in the calloc() function. However, older compiler versions don't support this built-in. This patch changes the overflow checking mechanism to make it work on any compiler version by using a division method to check for overflow. No functional change intended. While in there, remove the unused variable `void *orig`. Link: https://lore.kernel.org/lkml/20220330024114.GA18892@xxxxxx Suggested-by: Willy Tarreau <w@xxxxxx> Cc: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx> Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx> Acked-by: Willy Tarreau <w@xxxxxx> Reviewed-by: Alviro Iskandar Setiawan <alviro.iskandar@xxxxxxxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- tools/include/nolibc/stdlib.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/tools/include/nolibc/stdlib.h b/tools/include/nolibc/stdlib.h index 8fd32eaf80370..92378c4b96605 100644 --- a/tools/include/nolibc/stdlib.h +++ b/tools/include/nolibc/stdlib.h @@ -128,10 +128,9 @@ void *malloc(size_t len) static __attribute__((unused)) void *calloc(size_t size, size_t nmemb) { - void *orig; - size_t res = 0; + size_t x = size * nmemb; - if (__builtin_expect(__builtin_mul_overflow(nmemb, size, &res), 0)) { + if (__builtin_expect(size && ((x / size) != nmemb), 0)) { SET_ERRNO(ENOMEM); return NULL; } @@ -140,7 +139,7 @@ void *calloc(size_t size, size_t nmemb) * No need to zero the heap, the MAP_ANONYMOUS in malloc() * already does it. */ - return malloc(res); + return malloc(x); } static __attribute__((unused)) -- 2.31.1.189.g2e36527f23
