CVE-2026-80802: nfc: fdp: bound the device-reported read length and fix an skb leak

CVE-2026-80802: nfc: fdp: bound the device-reported read length and fix an skb leak

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

nfc: fdp: bound the device-reported read length and fix an skb leak

fdp_nci_i2c_read() takes the next packet length from two device-supplied
bytes and never validates it. The value is a u16 used as the
i2c_master_recv() count into a 261-byte on-stack buffer: a malicious,
counterfeit or malfunctioning controller (or an i2c bus interposer) can
drive it far past the buffer for a stack out-of-bounds write that
clobbers the canary and return address, or below the minimum frame size
(directly, or by truncating the computed sum) so the header/LRC strip
and the next length read run past a short receive. Reject a length
outside [FDP_NCI_I2C_MIN_PAYLOAD, FDP_NCI_I2C_MAX_PAYLOAD], as a
corrupted packet already is, and force resynchronization.

The same loop allocates one data skb per iteration and assumes a length
packet followed by a data packet; a device that sends two data packets
in one call leaks the first skb when the second allocation overwrites
it. Free a previously allocated skb before allocating the next.

The Linux kernel CVE team has assigned CVE-2026-80802 to this issue.


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

	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 5.10.267 with commit d9498ab9a78cb63d78dbe4f221d8cc6c91f285ee
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 5.15.218 with commit 1fc32327b927a6e2cde086f82575c29880844228
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 6.1.185 with commit 8d2c243b79854628ff076c38748c020042f02f57
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 6.6.154 with commit fc3c2bd5b1ec6c7cbc8a50e32d9bcec114f25463
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 6.12.106 with commit 0d723090645b82c1cb27cfd7ebf81f0e7c96bcae
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 6.18.47 with commit db7e464b350969c6ea8340de00d9796e5fd5123b
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 7.1.11 with commit e5eec121f2c3bc4c7022613bedd9121a8aa4c949
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 7.2.1 with commit 1aa3fc769b0c45bd19f8dab1697084c2b3f6d706
	Issue introduced in 4.4 with commit a06347c04c13e380afce0c9816df51f00b83faf1 and fixed in 7.3-rc1 with commit 7ad21dcfeb5181af0c3ee2608808c0c0a5283aa1

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-2026-80802
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/nfc/fdp/i2c.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/d9498ab9a78cb63d78dbe4f221d8cc6c91f285ee
	https://git.kernel.org/stable/c/1fc32327b927a6e2cde086f82575c29880844228
	https://git.kernel.org/stable/c/8d2c243b79854628ff076c38748c020042f02f57
	https://git.kernel.org/stable/c/fc3c2bd5b1ec6c7cbc8a50e32d9bcec114f25463
	https://git.kernel.org/stable/c/0d723090645b82c1cb27cfd7ebf81f0e7c96bcae
	https://git.kernel.org/stable/c/db7e464b350969c6ea8340de00d9796e5fd5123b
	https://git.kernel.org/stable/c/e5eec121f2c3bc4c7022613bedd9121a8aa4c949
	https://git.kernel.org/stable/c/1aa3fc769b0c45bd19f8dab1697084c2b3f6d706
	https://git.kernel.org/stable/c/7ad21dcfeb5181af0c3ee2608808c0c0a5283aa1