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