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From cb2595c1393b4a5211534e6f0a0fbad369e21ad8 Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 1 Jun 2018 11:31:44 -0700
Subject: [PATCH] infiniband: fix a possible use-after-free bug
ucma_process_join() will free the new allocated "mc" struct,
if there is any error after that, especially the copy_to_user().
But in parallel, ucma_leave_multicast() could find this "mc"
through idr_find() before ucma_process_join() frees it, since it
is already published.
So "mc" could be used in ucma_leave_multicast() after it is been
allocated and freed in ucma_process_join(), since we don't refcnt
it.
Fix this by separating "publish" from ID allocation, so that we
can get an ID first and publish it later after copy_to_user().
CVE: CVE-2018-14734
Upstream-Status: Backport
Fixes: c8f6a362bf3e ("RDMA/cma: Add multicast communication support")
Reported-by: Noam Rathaus <noamr@beyondsecurity.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
---
drivers/infiniband/core/ucma.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index eab43b1..ec8fb28 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx)
return NULL;
mutex_lock(&mut);
- mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL);
+ mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL);
mutex_unlock(&mut);
if (mc->id < 0)
goto error;
@@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct ucma_file *file,
goto err3;
}
+ mutex_lock(&mut);
+ idr_replace(&multicast_idr, mc, mc->id);
+ mutex_unlock(&mut);
+
mutex_unlock(&file->mut);
ucma_put_ctx(ctx);
return 0;
--
2.7.4
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