Re: [PATCH] rds: Error on offset mismatch if not loopback

Attempting an rds connection from the IP address of an IPoIB interface
to itself causes a kernel panic due to a BUG_ON() being triggered.
Making the test less strict allows rds-ping to work without crashing
the machine.

A local unprivileged user could use this flaw to crash the system.

Signed-off-by: John Jolly<redacted>
---
  net/rds/ib_send.c |    2 +-
  1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index e590949..7920c85 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c

@@ -544,7 +544,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
         int flow_controlled = 0;
         int nr_sig = 0;

-       BUG_ON(off % RDS_FRAG_SIZE);
+       BUG_ON(!conn->c_loopback&&  off % RDS_FRAG_SIZE);
         BUG_ON(hdr_off != 0&&  hdr_off != sizeof(struct rds_header));

         /* Do not send cong updates to IB loopback */