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Safa Karakuş 4072177348 Bluetooth: fix UAF in l2cap_sock_cleanup_listen() vs l2cap_conn_del() 
[ Upstream commit ab1513597c ]

bt_accept_dequeue() unlinks a not-yet-accepted child from the parent
accept queue and release_sock()s it before returning, so the returned
sk has no caller reference and is unlocked.

l2cap_sock_cleanup_listen() walks these children on listening-socket
close.  A concurrent HCI disconnect drives hci_rx_work ->
l2cap_conn_del() which runs l2cap_chan_del() + l2cap_sock_kill() and
frees the child sk and its l2cap_chan; cleanup_listen() then uses both:

  BUG: KASAN: slab-use-after-free in l2cap_sock_kill
    l2cap_sock_kill / l2cap_sock_cleanup_listen / __x64_sys_close
  Freed by: l2cap_conn_del -> l2cap_sock_close_cb -> l2cap_sock_kill

This is distinct from the two fixes already in this area: commit
e83f5e24da ("Bluetooth: serialize accept_q access") serialises the
accept_q list/poll and takes temporary refs inside bt_accept_dequeue(),
and CVE-2025-39860 serialises the userspace close()/accept() race by
calling cleanup_listen() under lock_sock() in l2cap_sock_release().
Neither covers l2cap_conn_del() running from hci_rx_work, so this UAF
still reproduces on current bluetooth/master.

Take the reference at the source: bt_accept_dequeue() does sock_hold()
while sk is still locked, before release_sock(); callers sock_put().
cleanup_listen() pins the chan with l2cap_chan_hold_unless_zero() under
a brief child sk lock (serialising vs l2cap_sock_teardown_cb()), drops
it before l2cap_chan_lock(), and skips a duplicate l2cap_sock_kill() on
SOCK_DEAD.  conn->lock is not taken here: cleanup_listen() runs under
the parent sk lock and that would invert
conn->lock -> chan->lock -> sk_lock (lockdep).

KASAN/SMP: an unprivileged listen/close vs HCI-disconnect race produced
12 use-after-free reports per run before this change; 0, and no lockdep
report, over 1600+ raced iterations after it on bluetooth/master.

Fixes: 15f02b9105 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Cc: stable@vger.kernel.org
Reported-by: Siwei Zhang <oss@fourdim.xyz>
Reviewed-by: Siwei Zhang <oss@fourdim.xyz>
Signed-off-by: Safa Karakuş <safa.karakus@secunnix.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-06-19 13:33:45 +02:00
arch arm64/mm: Enable batched TLB flush in unmap_hotplug_range() 2026-06-19 13:33:40 +02:00
block blk-mq: use quiesced elevator switch when reinitializing queues 2026-06-01 17:35:09 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: af_alg - Cap AEAD AD length to 0x80000000 2026-06-01 17:35:44 +02:00
Documentation Documentation: fix a hugetlbfs reservation statement 2026-06-01 17:35:32 +02:00
drivers spi: lantiq-ssc: fix controller deregistration 2026-06-19 13:33:45 +02:00
fs smb: client: require net admin for CIFS SWN netlink 2026-06-19 13:33:45 +02:00
include genetlink: Use internal flags for multicast groups 2026-06-19 13:33:45 +02:00
init randomize_kstack: Maintain kstack_offset per task 2026-06-19 13:33:41 +02:00
io_uring io_uring/poll: fix signed comparison in io_poll_get_ownership() 2026-06-19 13:33:39 +02:00
ipc ipc/shm: serialize orphan cleanup with shm_nattch updates 2026-06-19 13:33:38 +02:00
kernel tracing/probes: Limit size of event probe to 3K 2026-06-19 13:33:44 +02:00
lib lib/crypto: mpi: Fix integer underflow in mpi_read_raw_from_sgl() 2026-06-19 13:33:39 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/hugetlb_cma: round up per_node before logging it 2026-06-19 13:33:44 +02:00
net
samples samples: mei: Fix building on musl libc 2025-08-28 16:24:07 +02:00
scripts scripts/dtc: Remove unused dts_version in dtc-lexer.l 2026-06-01 17:35:12 +02:00
security ima: check return value of crypto_shash_final() in boot aggregate 2026-06-01 17:35:34 +02:00
sound ALSA: aloop: Fix peer runtime UAF during format-change stop 2026-06-19 13:33:42 +02:00
tools selftests: forwarding: lib: Add helpers for checksum handling 2026-06-19 13:33:24 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Reject wrapped offset in kvm_reset_dirty_gfn() 2026-06-01 17:35:44 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS staging: rtl8712: Remove driver using deprecated API wext 2025-12-07 06:09:36 +09:00
Makefile Linux 5.15.209 2026-06-01 17:35:51 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.