CVE-2026-80795: nfc: nci: fix out-of-bounds write in nci_target_auto_activated()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

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

nfc: nci: fix out-of-bounds write in nci_target_auto_activated()

nci_target_auto_activated() appends a target to the fixed-size array
ndev->targets[NCI_MAX_DISCOVERED_TARGETS] and increments ndev->n_targets
without first checking the array is full; unlike its sibling
nci_add_new_target(), which bails out when n_targets already equals
NCI_MAX_DISCOVERED_TARGETS.

ndev->n_targets is only cleared by nci_clear_target_list(), so an NFCC
that repeatedly re-runs discovery (RF_DISCOVER_RSP, which re-enters
NCI_DISCOVERY without clearing the target list) and reports an
auto-activated target (RF_INTF_ACTIVATED_NTF) drives n_targets past the
limit. The append then writes a struct nfc_target past the end of the
array (a slab out-of-bounds write), and nfc_targets_found() goes on to
walk the array with the inflated count:

  BUG: KASAN: slab-out-of-bounds in nci_add_new_protocol+0x94/0x2ac [nci]
  Write of size 2 at addr ffff0000c7299a18 by task kworker/u8:0/12
  Workqueue: nfc0_nci_rx_wq nci_rx_work [nci]
  Call trace:
   nci_add_new_protocol+0x94/0x2ac [nci]
   nci_ntf_packet+0xddc/0x11a0 [nci]
   nci_rx_work+0x15c/0x1e0 [nci]
   process_one_work+0x2dc/0x500
   worker_thread+0x240/0x460
   kthread+0x1c0/0x1d0
   ret_from_fork+0x10/0x20

  The buggy address belongs to the cache kmalloc-2k of size 2048
  The buggy address is located 1024 bytes to the right of
  allocated 1560-byte region [ffff0000c7299000, ffff0000c7299618)

Guard nci_target_auto_activated() with the same check used by
nci_add_new_target().

The Linux kernel CVE team has assigned CVE-2026-80795 to this issue.


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

	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 5.10.267 with commit 0dc59de0075f88404a0f4a2b5233104ef459fbb2
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 5.15.218 with commit 94530ffabfca57e9bff1d207106010014cc84032
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 6.1.185 with commit afd8605fb43becb892311102844955c3b127fc7e
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 6.6.154 with commit 24761d3a5f692df5f7d848caeabcb2afd10917aa
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 6.12.106 with commit 50e87e1c0e18d791dcd7dccf30f9a2f3e2cf3951
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 6.18.47 with commit 2f08dbce3b37624ec6b424d759336a99586170ec
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 7.1.11 with commit d7083f41c21b30582e91b2e6de4d54dce74f6f9c
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 7.2.1 with commit 129032c0616d83a5e3e304f6ebf88f14ba01e5f7
	Issue introduced in 3.4 with commit 019c4fbaa790e2b3f11dab0c8b7d9896d77db3e5 and fixed in 7.3-rc1 with commit ac200079db50af81e6b04d058b33ec92901d8edd

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-2026-80795
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:
	net/nfc/nci/ntf.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/0dc59de0075f88404a0f4a2b5233104ef459fbb2
	https://git.kernel.org/stable/c/94530ffabfca57e9bff1d207106010014cc84032
	https://git.kernel.org/stable/c/afd8605fb43becb892311102844955c3b127fc7e
	https://git.kernel.org/stable/c/24761d3a5f692df5f7d848caeabcb2afd10917aa
	https://git.kernel.org/stable/c/50e87e1c0e18d791dcd7dccf30f9a2f3e2cf3951
	https://git.kernel.org/stable/c/2f08dbce3b37624ec6b424d759336a99586170ec
	https://git.kernel.org/stable/c/d7083f41c21b30582e91b2e6de4d54dce74f6f9c
	https://git.kernel.org/stable/c/129032c0616d83a5e3e304f6ebf88f14ba01e5f7
	https://git.kernel.org/stable/c/ac200079db50af81e6b04d058b33ec92901d8edd