From: Jakub Kicinski Date: Mon, 23 Oct 2023 15:23:44 +0000 (-0700) Subject: net: trust the bitmap in __dev_alloc_name() X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7ad17b04dc7bdcdd1f85e460c38da55b0afa2422;p=linux.git net: trust the bitmap in __dev_alloc_name() Prior to restructuring __dev_alloc_name() handled both printf and non-printf names. In a clever attempt at code reuse it always prints the name into a buffer and checks if it's a duplicate. Trust the bitmap, and return an error if its full. This shrinks the possible ID space by one from 32K to 32K - 1, as previously the max value would have been tried as a valid ID. It seems very unlikely that anyone would care as we heard no requests to increase the max beyond 32k. Reviewed-by: Jiri Pirko Link: https://lore.kernel.org/r/20231023152346.3639749-5-kuba@kernel.org Signed-off-by: Jakub Kicinski --- diff --git a/net/core/dev.c b/net/core/dev.c index bbfb02b4a228c..d2698b4bbad4f 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -1119,18 +1119,11 @@ static int __dev_alloc_name(struct net *net, const char *name, char *res) i = find_first_zero_bit(inuse, max_netdevices); bitmap_free(inuse); + if (i == max_netdevices) + return -ENFILE; - snprintf(buf, IFNAMSIZ, name, i); - if (!netdev_name_in_use(net, buf)) { - strscpy(res, buf, IFNAMSIZ); - return i; - } - - /* It is possible to run out of possible slots - * when the name is long and there isn't enough space left - * for the digits, or if all bits are used. - */ - return -ENFILE; + snprintf(res, IFNAMSIZ, name, i); + return i; } /* Returns negative errno or allocated unit id (see __dev_alloc_name()) */