CVE-2024-56712 Information

Description

In the Linux kernel the following vulnerability has been resolved:

udmabuf: fix memory leak on last export_udmabuf() error path

In export_udmabuf() if dma_buf_fd() fails because the FD table is full a dma_buf owning the udmabuf has already been created; but the error handling in udmabuf_create() will tear down the udmabuf without doing anything about the containing dma_buf.

This leaves a dma_buf in memory that contains a dangling pointer; though that doesn’t seem to lead to anything bad except a memory leak.

Fix it by moving the dma_buf_fd() call out of export_udmabuf() so that we can give it different error handling.

Note that the shape of this code changed a lot in commit 5e72b2b41a21 ( mabuf: convert udmabuf driver to use folios); but the memory leak seems to have existed since the introduction of udmabuf.

Reference

https://git.kernel.org/stable/c/c9fc8428d4255c2128da9c4d5cd92e554d0150cf https://git.kernel.org/stable/c/f49856f525acd5bef52ae28b7da2e001bbe7439e