From 9bd2bbc01d17ddd567cc0f81f77fe1163e497462 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 2 Jun 2017 20:35:51 -0700 Subject: [PATCH] elevator: fix truncation of icq_cache_name MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit gcc 7.1 reports the following warning: block/elevator.c: In function ‘elv_register’: block/elevator.c:898:5: warning: ‘snprintf’ output may be truncated before the last format character [-Wformat-truncation=] "%s_io_cq", e->elevator_name); ^~~~~~~~~~ block/elevator.c:897:3: note: ‘snprintf’ output between 7 and 22 bytes into a destination of size 21 snprintf(e->icq_cache_name, sizeof(e->icq_cache_name), ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "%s_io_cq", e->elevator_name); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The bug is that the name of the icq_cache is 6 characters longer than the elevator name, but only ELV_NAME_MAX + 5 characters were reserved for it --- so in the case of a maximum-length elevator name, the 'q' character in "_io_cq" would be truncated by snprintf(). Fix it by reserving ELV_NAME_MAX + 6 characters instead. Signed-off-by: Eric Biggers Reviewed-by: Bart Van Assche Signed-off-by: Jens Axboe --- include/linux/elevator.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/elevator.h b/include/linux/elevator.h index 9ec5e22846e0..0e306c5a86d6 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -153,7 +153,7 @@ struct elevator_type #endif /* managed by elevator core */ - char icq_cache_name[ELV_NAME_MAX + 5]; /* elvname + "_io_cq" */ + char icq_cache_name[ELV_NAME_MAX + 6]; /* elvname + "_io_cq" */ struct list_head list; }; -- 2.20.1