linux-cve-announce - CVE-2021-47649: udmabuf: validate ubuf->pagecount

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Message-ID: <2025022649-CVE-2021-47649-f358@gregkh>
Date: Wed, 26 Feb 2025 02:54:00 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2021-47649: udmabuf: validate ubuf->pagecount

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

udmabuf: validate ubuf->pagecount

Syzbot has reported GPF in sg_alloc_append_table_from_pages(). The
problem was in ubuf->pages == ZERO_PTR.

ubuf->pagecount is calculated from arguments passed from user-space. If
user creates udmabuf with list.size == 0 then ubuf->pagecount will be
also equal to zero; it causes kmalloc_array() to return ZERO_PTR.

Fix it by validating ubuf->pagecount before passing it to
kmalloc_array().

The Linux kernel CVE team has assigned CVE-2021-47649 to this issue.


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

	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.4.189 with commit 5d50f851dd307c07ca5591297093f19967c834a9
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.10.110 with commit b267a8118c2b171bf7d67b90ed64154eeab9fae0
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.15.33 with commit 811b667cefbea9cb7511a874b169d6a92907137e
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.16.19 with commit a3728d32fc61eb0fe283cb8ff60b2c8f751e2202
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.17.2 with commit 9e9b4a269f84d3230f2af84ff42322db676440d9
	Issue introduced in 4.20 with commit fbb0de795078190a9834b3409e4b009cfb18a6d4 and fixed in 5.18 with commit 2b6dd600dd72573c23ea180b5b0b2f1813405882

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-2021-47649
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/5d50f851dd307c07ca5591297093f19967c834a9
	https://git.kernel.org/stable/c/b267a8118c2b171bf7d67b90ed64154eeab9fae0
	https://git.kernel.org/stable/c/811b667cefbea9cb7511a874b169d6a92907137e
	https://git.kernel.org/stable/c/a3728d32fc61eb0fe283cb8ff60b2c8f751e2202
	https://git.kernel.org/stable/c/9e9b4a269f84d3230f2af84ff42322db676440d9
	https://git.kernel.org/stable/c/2b6dd600dd72573c23ea180b5b0b2f1813405882