Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1311293

[PATCH 3.2 42/70] net: possible use after free in dst_release

Show all headers | View raw

3.2.76-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Francesco Ruggeri <fruggeri@aristanetworks.com>

commit 07a5d38453599052aff0877b16bb9c1585f08609 upstream.

dst_release should not access dst->flags after decrementing
__refcnt to 0. The dst_entry may be in dst_busy_list and
dst_gc_task may dst_destroy it before dst_release gets a chance
to access dst->flags.

Fixes: d69bbf88c8d0 ("net: fix a race in dst_release()")
Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst")
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 net/core/dst.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -269,10 +269,11 @@ void dst_release(struct dst_entry *dst)
 {
 	if (dst) {
 		int newrefcnt;
+		unsigned short nocache = dst->flags & DST_NOCACHE;
 
 		newrefcnt = atomic_dec_return(&dst->__refcnt);
 		WARN_ON(newrefcnt < 0);
-		if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) {
+		if (!newrefcnt && unlikely(nocache)) {
 			dst = dst_destroy(dst);
 			if (dst)
 				__dst_free(dst);

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH 3.2 42/70] net: possible use after free in dst_release Ben Hutchings <ben@decadent.org.uk> - 2016-01-18 04:40 +0100
  Re: [PATCH 3.2 42/70] net: possible use after free in dst_release Francesco Ruggeri <fruggeri@arista.com> - 2016-01-18 04:50 +0100
    Re: [PATCH 3.2 42/70] net: possible use after free in dst_release Ben Hutchings <ben@decadent.org.uk> - 2016-01-18 13:00 +0100

csiph-web