linux-cve-announce - CVE-2024-56712: udmabuf: fix memory leak on last export

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Message-ID: <2024122914-CVE-2024-56712-d62a@gregkh>
Date: Sun, 29 Dec 2024 09:48:16 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56712: udmabuf: fix memory leak on last export_udmabuf() error path

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
("udmabuf: convert udmabuf driver to use folios"); but the memory leak
seems to have existed since the introduction of udmabuf.

The Linux kernel CVE team has assigned CVE-2024-56712 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 6.12.7 with commit c9fc8428d4255c2128da9c4d5cd92e554d0150cf
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 6.13-rc4 with commit f49856f525acd5bef52ae28b7da2e001bbe7439e

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-56712
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/dma-buf/udmabuf.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/c9fc8428d4255c2128da9c4d5cd92e554d0150cf
	https://git.kernel.org/stable/c/f49856f525acd5bef52ae28b7da2e001bbe7439e