net/haproxy/patches/008-BUG-MINOR-stick_table-Prevent-conn_cur-from-underflowing.patch

   1 commit 93b3994091b5bd17b43c9d91ecae470d33157e25
   2 Author: Tim Duesterhus <tim@bastelstu.be>
   3 Date:   Fri Jan 4 00:11:59 2019 +0100
   4
   5     BUG/MINOR: stick_table: Prevent conn_cur from underflowing
   6
   7     When using the peers feature a race condition could prevent
   8     a connection from being properly counted. When this connection
   9     exits it is being "uncounted" nonetheless, leading to a possible
  10     underflow (-1) of the conn_curr stick table entry in the following
  11     scenario :
  12
  13       - Connect to peer A     (A=1, B=0)
  14       - Peer A sends 1 to B   (A=1, B=1)
  15       - Kill connection to A  (A=0, B=1)
  16       - Connect to peer B     (A=0, B=2)
  17       - Peer A sends 0 to B   (A=0, B=0)
  18       - Peer B sends 0/2 to A (A=?, B=0)
  19       - Kill connection to B  (A=?, B=-1)
  20       - Peer B sends -1 to A  (A=-1, B=-1)
  21
  22     This fix may be backported to all supported branches.
  23
  24     (cherry picked from commit 8b87c01c4d59247d9fb51a38cd12d5d94324b6a4)
  25     Signed-off-by: Willy Tarreau <w@1wt.eu>
  26     (cherry picked from commit 4ceecc8a4ee6f46f20c7729056e14af5a8757121)
  27     Signed-off-by: William Lallemand <wlallemand@haproxy.org>
  28
  29 diff --git a/include/proto/session.h b/include/proto/session.h
  30 index f48c0d4f..7265f5a7 100644
  31 --- a/include/proto/session.h
  32 +++ b/include/proto/session.h
  33 @@ -59,7 +59,8 @@ static inline void session_store_counters(struct session *sess)
  34                 if (ptr) {
  35                         HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
  36
  37 -                       stktable_data_cast(ptr, conn_cur)--;
  38 +                       if (stktable_data_cast(ptr, conn_cur) > 0)
  39 +                               stktable_data_cast(ptr, conn_cur)--;
  40
  41                         HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
  42
  43 diff --git a/include/proto/stream.h b/include/proto/stream.h
  44 index 8521957e..c9bcac37 100644
  45 --- a/include/proto/stream.h
  46 +++ b/include/proto/stream.h
  47 @@ -104,7 +104,8 @@ static inline void stream_store_counters(struct stream *s)
  48                 if (ptr) {
  49                         HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
  50
  51 -                       stktable_data_cast(ptr, conn_cur)--;
  52 +                       if (stktable_data_cast(ptr, conn_cur) > 0)
  53 +                               stktable_data_cast(ptr, conn_cur)--;
  54
  55                         HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
  56
  57 @@ -142,7 +143,8 @@ static inline void stream_stop_content_counters(struct stream *s)
  58                 if (ptr) {
  59                         HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock);
  60
  61 -                       stktable_data_cast(ptr, conn_cur)--;
  62 +                       if (stktable_data_cast(ptr, conn_cur) > 0)
  63 +                               stktable_data_cast(ptr, conn_cur)--;
  64
  65                         HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock);
  66