netfilter: nf_log: fix direct userspace memory access in proc handler

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 11 insertions, 5 deletions

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 2fefe147750a..4e620305f28c 100644
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -47,7 +47,6 @@ int nf_log_register(u_int8_t pf, struct nf_logger *logger)
         mutex_lock(&nf_log_mutex);
 
         if (pf == NFPROTO_UNSPEC) {
-                int i;
                 for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
                         list_add_tail(&(logger->list[i]), &(nf_loggers_l[i]));
         } else {
@@ -216,7 +215,7 @@ static const struct file_operations nflog_file_ops = {
 #endif /* PROC_FS */
 
 #ifdef CONFIG_SYSCTL
-struct ctl_path nf_log_sysctl_path[] = {
+static struct ctl_path nf_log_sysctl_path[] = {
         { .procname = "net", .ctl_name = CTL_NET, },
         { .procname = "netfilter", .ctl_name = NET_NETFILTER, },
         { .procname = "nf_log", .ctl_name = CTL_UNNUMBERED, },
@@ -228,19 +227,26 @@ static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
 static struct ctl_table_header *nf_log_dir_header;
 
 static int nf_log_proc_dostring(ctl_table *table, int write, struct file *filp,
-                         void *buffer, size_t *lenp, loff_t *ppos)
+                         void __user *buffer, size_t *lenp, loff_t *ppos)
 {
         const struct nf_logger *logger;
+        char buf[NFLOGGER_NAME_LEN];
+        size_t size = *lenp;
         int r = 0;
         int tindex = (unsigned long)table->extra1;
 
         if (write) {
-                if (!strcmp(buffer, "NONE")) {
+                if (size > sizeof(buf))
+                        size = sizeof(buf);
+                if (copy_from_user(buf, buffer, size))
+                        return -EFAULT;
+
+                if (!strcmp(buf, "NONE")) {
                         nf_log_unbind_pf(tindex);
                         return 0;
                 }
                 mutex_lock(&nf_log_mutex);
-                logger = __find_logger(tindex, buffer);
+                logger = __find_logger(tindex, buf);
                 if (logger == NULL) {
                         mutex_unlock(&nf_log_mutex);
                         return -ENOENT;