From: Eric Biggers ebiggers@google.com
commit 9bd2bbc01d17ddd567cc0f81f77fe1163e497462 upstream.
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 ebiggers@google.com Reviewed-by: Bart Van Assche Bart.VanAssche@sandisk.com Signed-off-by: Jens Axboe axboe@fb.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/elevator.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -97,7 +97,7 @@ struct elevator_type struct module *elevator_owner;
/* 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; };