On Tue, Sep 07, 2021 at 03:00:23PM +0000, Chuck Lever III wrote: > We have IPV6_SCOPE_ID_LEN as a maximum size of the scope ID, > and it's not a big value. As long as boundary checking is made > to be sufficient, then a stack residency for the device name > should be safe. Something like this? (Or are you making a patch? I'm not even sure how to test.) --b. diff --git a/net/sunrpc/addr.c b/net/sunrpc/addr.c index 6e4dbd577a39..d435bffc6199 100644 --- a/net/sunrpc/addr.c +++ b/net/sunrpc/addr.c @@ -162,8 +162,10 @@ static int rpc_parse_scope_id(struct net *net, const char *buf, const size_t buflen, const char *delim, struct sockaddr_in6 *sin6) { - char *p; + char p[IPV6_SCOPE_ID_LEN + 1]; size_t len; + u32 scope_id = 0; + struct net_device *dev; if ((buf + buflen) == delim) return 1; @@ -175,29 +177,23 @@ static int rpc_parse_scope_id(struct net *net, const char *buf, return 0; len = (buf + buflen) - delim - 1; - p = kmemdup_nul(delim + 1, len, GFP_KERNEL); - if (p) { - u32 scope_id = 0; - struct net_device *dev; - - dev = dev_get_by_name(net, p); - if (dev != NULL) { - scope_id = dev->ifindex; - dev_put(dev); - } else { - if (kstrtou32(p, 10, &scope_id) != 0) { - kfree(p); - return 0; - } - } - - kfree(p); - - sin6->sin6_scope_id = scope_id; - return 1; + if (len > IPV6_SCOPE_ID_LEN) + return 0; + + memcpy(p, delim + 1, len); + p[len] = 0; + + dev = dev_get_by_name(net, p); + if (dev != NULL) { + scope_id = dev->ifindex; + dev_put(dev); + } else { + if (kstrtou32(p, 10, &scope_id) != 0) + return 0; } - return 0; + sin6->sin6_scope_id = scope_id; + return 1; } static size_t rpc_pton6(struct net *net, const char *buf, const size_t buflen,