From: Leon Romanovsky <leonro@mellanox.com>
Date: Mon, 19 Mar 2018 12:20:15 +0000 (+0200)
Subject: RDMA/ucma: Fix use-after-free access in ucma_close
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=e78759ba4d27ab2f19b285f666887bf4d00b7514

RDMA/ucma: Fix use-after-free access in ucma_close

commit ed65a4dc22083e73bac599ded6a262318cad7baf upstream.

The error in ucma_create_id() left ctx in the list of contexts belong
to ucma file descriptor. The attempt to close this file descriptor causes
to use-after-free accesses while iterating over such list.

Fixes: 75216638572f ("RDMA/cma: Export rdma cm interface to userspace")
Reported-by: <syzbot+dcfd344365a56fbebd0f@syzkaller.appspotmail.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 4396ab6df02a..0a8a39ce332e 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -433,6 +433,9 @@ err1:
 	mutex_lock(&mut);
 	idr_remove(&ctx_idr, ctx->id);
 	mutex_unlock(&mut);
+	mutex_lock(&file->mut);
+	list_del(&ctx->list);
+	mutex_unlock(&file->mut);
 	kfree(ctx);
 	return ret;
 }