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Aldo Ariel Panzardo 6e0241f6cb net/sched: serialize qdisc_rtab_list against concurrent get/put 
[ Upstream commit f43ee0c073 ]

qdisc_get_rtab() and qdisc_put_rtab() mutate the process-global singly
linked list qdisc_rtab_list and a plain non-atomic 'int refcnt' with no
lock. This was only safe because every caller historically held the RTNL
mutex, which serialized all rate-table lookups, inserts and frees.

That invariant no longer holds. cls_flower sets
TCF_PROTO_OPS_DOIT_UNLOCKED, so tc_new_tfilter() keeps rtnl_held == false
for it and sets TCA_ACT_FLAGS_NO_RTNL. That flag propagates through
tcf_exts_validate_ex() -> tcf_action_init() -> tcf_action_init_1() ->
tcf_police_init(), which calls qdisc_get_rtab()/qdisc_put_rtab() with the
RTNL mutex NOT held. Two RTM_NEWTFILTER requests on different CPUs, each
adding a flower filter with a police action carrying the same rate, then
race on qdisc_rtab_list and on the non-atomic refcnt, leading to a
use-after-free / double-free of the kmalloc-2k struct qdisc_rate_table.
qdisc_rtab_list is a single global (not per-netns), so the corrupted
object is shared system-wide.

  BUG: KASAN: slab-use-after-free in qdisc_put_rtab+0x12f/0x160
   qdisc_put_rtab+0x12f/0x160
   tcf_police_init+0xda9/0x1590
   tcf_action_init_1+0x460/0x6b0
   tcf_action_init+0x439/0xa40
   tcf_exts_validate_ex+0x42d/0x550
   fl_change+0xddd/0x7da0
   tc_new_tfilter+0xaa7/0x2420
   rtnetlink_rcv_msg+0x95e/0xe90
  which belongs to the cache kmalloc-2k of size 2048

Protect qdisc_rtab_list and the refcount with a dedicated spinlock. The
(sleeping, GFP_KERNEL) allocation in qdisc_get_rtab() is performed before
taking the lock; if a concurrent inserter added an identical table in the
meantime the freshly allocated one is freed under the lock, so no
duplicate is leaked. qdisc_put_rtab() now decrements the refcount and
unlinks under the same lock.

Fixes: 470502de5b ("net: sched: unlock rules update API")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Aldo Ariel Panzardo <qwe.aldo@gmail.com>
Cc: stable@vger.kernel.org
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260715114114.446841-1-qwe.aldo@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-08-23 14:17:28 +02:00
arch fs/resctrl: Fix double-add of pseudo-locked region's RMID to free list 2026-08-23 14:17:24 +02:00
block partitions: aix: bound the pp_count scan to the ppe array 2026-07-24 15:51:24 +02:00
certs X.509: Fix validation of ASN.1 certificate header 2026-07-24 15:51:59 +02:00
crypto crypto: rsa-pkcs1pad: Don't WARN on an empty digest 2026-08-19 17:13:55 +02:00
Documentation PCI: Move Resizable BAR code to rebar.c 2026-07-24 15:51:58 +02:00
drivers serial: sc16is7xx: implement gpio get_direction() callback 2026-08-23 14:17:27 +02:00
fs ksmbd: defer destroy_previous_session() until after NTLM authentication 2026-08-23 14:17:28 +02:00
include libceph: add doutc and *_client debug macros support 2026-08-23 14:17:27 +02:00
init bootconfig: move xbc_snprint_cmdline() to lib/bootconfig.c 2026-08-23 14:17:24 +02:00
io_uring io_uring/io-wq: re-check IO_WQ_BIT_EXIT for each linked work item 2026-07-24 15:51:21 +02:00
ipc ipc/shm: serialize orphan cleanup with shm_nattch updates 2026-06-19 13:33:38 +02:00
kernel locking/rt: Fix the incorrect RCU protection in rt_spin_unlock() 2026-08-23 14:17:23 +02:00
lib bootconfig: fix NULL-pointer arithmetic in xbc_snprint_cmdline() 2026-08-23 14:17:24 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: do file ownership checks with the proper mount idmap 2026-08-23 14:17:17 +02:00
net
samples tracing/events: Fix to check the simple_tsk_fn creation 2026-07-24 15:51:42 +02:00
scripts kconfig: fix potential NULL pointer dereference in conf_askvalue 2026-07-24 15:51:28 +02:00
security selinux: avoid sk_socket dereference in selinux_sctp_bind_connect() 2026-08-23 14:17:21 +02:00
sound ALSA: seq: close a re-opened queue timer in the destructor 2026-08-23 14:17:26 +02:00
tools selftests/ftrace: refactor eprobes test to fix argument checks 2026-08-19 17:14:13 +02:00
usr kbuild: hdrcheck: fix cross build with clang 2025-06-27 11:05:22 +01:00
virt KVM: Move kvm_io_bus_get_dev() locking responsibilities to callers 2026-07-24 15:52:02 +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 5.15.216 2026-08-19 17:14:18 +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.