From: Eric Dumazet <eduma...@google.com>
3.4.113-rc1 review patch. If anyone has any objections, please let me know.
------------------
commit d69bbf88c8d0b367cf3e3a052f6daadf630ee566 upstream.
Only cpu seeing dst refcount going to 0 can safely
dereference dst->flags.
Otherwise an other cpu might already have freed the dst.
Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst")
Reported-by: Greg Thelen <gthe...@google.com>
Signed-off-by: Eric Dumazet <eduma...@google.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lize...@huawei.com>
---
net/core/dst.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/dst.c b/net/core/dst.c
index 43d94ce..54ba1eb 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -272,7 +272,7 @@ void dst_release(struct dst_entry *dst)
newrefcnt = atomic_dec_return(&dst->__refcnt);
WARN_ON(newrefcnt < 0);
- if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt) {
+ if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) {
dst = dst_destroy(dst);
if (dst)
__dst_free(dst);
--
1.9.1
