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 4396ab6..0a8a39c 100644 (file)
--- 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;
 }