4.4-stable review patch. If anyone has any objections, please let me know.
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From: Cong Wang xiyou.wangcong@gmail.com
commit 5fe23f262e0548ca7f19fb79f89059a60d087d22 upstream.
There is a race condition between ucma_close() and ucma_resolve_ip():
CPU0 CPU1 ucma_resolve_ip(): ucma_close():
ctx = ucma_get_ctx(file, cmd.id);
list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) { mutex_lock(&mut); idr_remove(&ctx_idr, ctx->id); mutex_unlock(&mut); ... mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); rdma_destroy_id(ctx->cm_id); ... ucma_free_ctx(ctx);
ret = rdma_resolve_addr(); ucma_put_ctx(ctx);
Before idr_remove(), ucma_get_ctx() could still find the ctx and after rdma_destroy_id(), rdma_resolve_addr() may still access id_priv pointer. Also, ucma_put_ctx() may use ctx after ucma_free_ctx() too.
ucma_close() should call ucma_put_ctx() too which tests the refcnt and waits for the last one releasing it. The similar pattern is already used by ucma_destroy_id().
Reported-and-tested-by: syzbot+da2591e115d57a9cbb8b@syzkaller.appspotmail.com Reported-by: syzbot+cfe3c1e8ef634ba8964b@syzkaller.appspotmail.com Cc: Jason Gunthorpe jgg@mellanox.com Cc: Doug Ledford dledford@redhat.com Cc: Leon Romanovsky leon@kernel.org Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Leon Romanovsky leonro@mellanox.com Signed-off-by: Doug Ledford dledford@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/infiniband/core/ucma.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1709,6 +1709,8 @@ static int ucma_close(struct inode *inod mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); + ucma_put_ctx(ctx); + wait_for_completion(&ctx->comp); /* rdma_destroy_id ensures that no event handlers are * inflight for that id before releasing it. */