gen_stats.c: Duplicate xstats buffer for later use

[ Upstream commit 1c4cff0cf55011792125b6041bc4e9713e46240f ]

The gnet_stats_copy_app() function gets called, more often than not, with its
second argument a pointer to an automatic variable in the caller's stack.
Therefore, to avoid copying garbage afterwards when calling
gnet_stats_finish_copy(), this data is better copied to a dynamically allocated
memory that gets freed after use.

[xiyou.wangcong@gmail.com: remove a useless kfree()]

Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/core/gen_stats.c b/net/core/gen_stats.c
index 0452eb2..91080c1 100644 (file)
--- a/net/core/gen_stats.c
+++ b/net/core/gen_stats.c
@@ -31,6 +31,9 @@ gnet_stats_copy(struct gnet_dump *d, int type, void *buf, int size)
        return 0;
 
 nla_put_failure:
        return 0;
 
 nla_put_failure:

+       kfree(d->xstats);
+       d->xstats = NULL;
+       d->xstats_len = 0;

        spin_unlock_bh(d->lock);
        return -1;
 }
        spin_unlock_bh(d->lock);
        return -1;
 }


@@ -204,7 +207,9 @@ int
 gnet_stats_copy_app(struct gnet_dump *d, void *st, int len)
 {
        if (d->compat_xstats) {
 gnet_stats_copy_app(struct gnet_dump *d, void *st, int len)
 {
        if (d->compat_xstats) {

-               d->xstats = st;
+               d->xstats = kmemdup(st, len, GFP_ATOMIC);
+               if (!d->xstats)
+                       goto err_out;

                d->xstats_len = len;
        }
 
                d->xstats_len = len;
        }
 


@@ -212,6 +217,11 @@ gnet_stats_copy_app(struct gnet_dump *d, void *st, int len)
                return gnet_stats_copy(d, TCA_STATS_APP, st, len);
 
        return 0;
                return gnet_stats_copy(d, TCA_STATS_APP, st, len);
 
        return 0;

+
+err_out:
+       d->xstats_len = 0;
+       spin_unlock_bh(d->lock);
+       return -1;

 }
 EXPORT_SYMBOL(gnet_stats_copy_app);
 
 }
 EXPORT_SYMBOL(gnet_stats_copy_app);
 


@@ -244,6 +254,9 @@ gnet_stats_finish_copy(struct gnet_dump *d)
                        return -1;
        }
 
                        return -1;
        }
 

+       kfree(d->xstats);
+       d->xstats = NULL;
+       d->xstats_len = 0;

        spin_unlock_bh(d->lock);
        return 0;
 }
        spin_unlock_bh(d->lock);
        return 0;
 }