linux-cve-announce - CVE-2024-53058: net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data

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Message-ID: <2024111928-CVE-2024-53058-7bd0@gregkh>
Date: Tue, 19 Nov 2024 18:19:40 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-53058: net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data

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

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

net: stmmac: TSO: Fix unbalanced DMA map/unmap for non-paged SKB data

In case the non-paged data of a SKB carries protocol header and protocol
payload to be transmitted on a certain platform that the DMA AXI address
width is configured to 40-bit/48-bit, or the size of the non-paged data
is bigger than TSO_MAX_BUFF_SIZE on a certain platform that the DMA AXI
address width is configured to 32-bit, then this SKB requires at least
two DMA transmit descriptors to serve it.

For example, three descriptors are allocated to split one DMA buffer
mapped from one piece of non-paged data:
    dma_desc[N + 0],
    dma_desc[N + 1],
    dma_desc[N + 2].
Then three elements of tx_q->tx_skbuff_dma[] will be allocated to hold
extra information to be reused in stmmac_tx_clean():
    tx_q->tx_skbuff_dma[N + 0],
    tx_q->tx_skbuff_dma[N + 1],
    tx_q->tx_skbuff_dma[N + 2].
Now we focus on tx_q->tx_skbuff_dma[entry].buf, which is the DMA buffer
address returned by DMA mapping call. stmmac_tx_clean() will try to
unmap the DMA buffer _ONLY_IF_ tx_q->tx_skbuff_dma[entry].buf
is a valid buffer address.

The expected behavior that saves DMA buffer address of this non-paged
data to tx_q->tx_skbuff_dma[entry].buf is:
    tx_q->tx_skbuff_dma[N + 0].buf = NULL;
    tx_q->tx_skbuff_dma[N + 1].buf = NULL;
    tx_q->tx_skbuff_dma[N + 2].buf = dma_map_single();
Unfortunately, the current code misbehaves like this:
    tx_q->tx_skbuff_dma[N + 0].buf = dma_map_single();
    tx_q->tx_skbuff_dma[N + 1].buf = NULL;
    tx_q->tx_skbuff_dma[N + 2].buf = NULL;

On the stmmac_tx_clean() side, when dma_desc[N + 0] is closed by the
DMA engine, tx_q->tx_skbuff_dma[N + 0].buf is a valid buffer address
obviously, then the DMA buffer will be unmapped immediately.
There may be a rare case that the DMA engine does not finish the
pending dma_desc[N + 1], dma_desc[N + 2] yet. Now things will go
horribly wrong, DMA is going to access a unmapped/unreferenced memory
region, corrupted data will be transmited or iommu fault will be
triggered :(

In contrast, the for-loop that maps SKB fragments behaves perfectly
as expected, and that is how the driver should do for both non-paged
data and paged frags actually.

This patch corrects DMA map/unmap sequences by fixing the array index
for tx_q->tx_skbuff_dma[entry].buf when assigning DMA buffer address.

Tested and verified on DWXGMAC CORE 3.20a

The Linux kernel CVE team has assigned CVE-2024-53058 to this issue.


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

	Issue introduced in 4.7 with commit f748be531d70 and fixed in 5.15.171 with commit ece593fc9c00
	Issue introduced in 4.7 with commit f748be531d70 and fixed in 6.1.116 with commit a3ff23f7c3f0
	Issue introduced in 4.7 with commit f748be531d70 and fixed in 6.6.60 with commit 07c9c26e3754
	Issue introduced in 4.7 with commit f748be531d70 and fixed in 6.11.7 with commit 58d23d835eb4
	Issue introduced in 4.7 with commit f748be531d70 and fixed in 6.12 with commit 66600fac7a98

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-2024-53058
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/net/ethernet/stmicro/stmmac/stmmac_main.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/ece593fc9c00741b682869d3f3dc584d37b7c9df
	https://git.kernel.org/stable/c/a3ff23f7c3f0e13f718900803e090fd3997d6bc9
	https://git.kernel.org/stable/c/07c9c26e37542486e34d767505e842f48f29c3f6
	https://git.kernel.org/stable/c/58d23d835eb498336716cca55b5714191a309286
	https://git.kernel.org/stable/c/66600fac7a984dea4ae095411f644770b2561ede