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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().

Fixes: c8f6a362bf ("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>
hifive-unleashed-5.1
Cong Wang 2018-06-01 11:31:44 -07:00 committed by Jason Gunthorpe
parent e4b1672ac0
commit cb2595c139
1 changed files with 5 additions and 1 deletions
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6
drivers/infiniband/core/ucma.c
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@ -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;