[FIB]: Avoid using static variables without proper locking

fib_trie_seq_show() uses two helper functions, rtn_scope() and
rtn_type() that can write to static storage without locking.

Just pass to them a temporary buffer to avoid potential corruption
(probably not triggerable but still...)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 18fb73958a49a7d856743d450adcff8f4c822a24..72c78c2209d55acde507b44541aeaf2c371f66c5 100644 (file)
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2284,10 +2284,8 @@ static void seq_indent(struct seq_file *seq, int n)
        while (n-- > 0) seq_puts(seq, "   ");
 }
 
-static inline const char *rtn_scope(enum rt_scope_t s)
+static inline const char *rtn_scope(char *buf, size_t len, enum rt_scope_t s)
 {
-       static char buf[32];
-
        switch (s) {
        case RT_SCOPE_UNIVERSE: return "universe";
        case RT_SCOPE_SITE:     return "site";
@@ -2295,7 +2293,7 @@ static inline const char *rtn_scope(enum rt_scope_t s)
        case RT_SCOPE_HOST:     return "host";
        case RT_SCOPE_NOWHERE:  return "nowhere";
        default:
-               snprintf(buf, sizeof(buf), "scope=%d", s);
+               snprintf(buf, len, "scope=%d", s);
                return buf;
        }
 }
@@ -2315,13 +2313,11 @@ static const char *rtn_type_names[__RTN_MAX] = {
        [RTN_XRESOLVE] = "XRESOLVE",
 };
 
-static inline const char *rtn_type(unsigned t)
+static inline const char *rtn_type(char *buf, size_t len, unsigned t)
 {
-       static char buf[32];
-
        if (t < __RTN_MAX && rtn_type_names[t])
                return rtn_type_names[t];
-       snprintf(buf, sizeof(buf), "type %u", t);
+       snprintf(buf, len, "type %u", t);
        return buf;
 }
 
@@ -2359,13 +2355,19 @@ static int fib_trie_seq_show(struct seq_file *seq, void *v)
                seq_printf(seq, "  |-- %d.%d.%d.%d\n", NIPQUAD(val));
                for (i = 32; i >= 0; i--) {
                        struct leaf_info *li = find_leaf_info(l, i);
+
                        if (li) {
                                struct fib_alias *fa;
+
                                list_for_each_entry_rcu(fa, &li->falh, fa_list) {
+                                       char buf1[32], buf2[32];
+
                                        seq_indent(seq, iter->depth+1);
                                        seq_printf(seq, "  /%d %s %s", i,
-                                                  rtn_scope(fa->fa_scope),
-                                                  rtn_type(fa->fa_type));
+                                                  rtn_scope(buf1, sizeof(buf1),
+                                                            fa->fa_scope),
+                                                  rtn_type(buf2, sizeof(buf2),
+                                                            fa->fa_type));
                                        if (fa->fa_tos)
                                                seq_printf(seq, "tos =%d\n",
                                                           fa->fa_tos);