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Filename Latest commit message Latest commit date
Pedro Tammela e5bee633cc net_sched: hfsc: Address reentrant enqueue adding class to eltree twice
commit ac9fe7dd8e730a103ae4481147395cc73492d786 upstream.

Savino says:
    "We are writing to report that this recent patch
    (141d34391abbb315d68556b7c67ad97885407547) [1]
    can be bypassed, and a UAF can still occur when HFSC is utilized with
    NETEM.

    The patch only checks the cl->cl_nactive field to determine whether
    it is the first insertion or not [2], but this field is only
    incremented by init_vf [3].

    By using HFSC_RSC (which uses init_ed) [4], it is possible to bypass the
    check and insert the class twice in the eltree.
    Under normal conditions, this would lead to an infinite loop in
    hfsc_dequeue for the reasons we already explained in this report [5].

    However, if TBF is added as root qdisc and it is configured with a
    very low rate,
    it can be utilized to prevent packets from being dequeued.
    This behavior can be exploited to perform subsequent insertions in the
    HFSC eltree and cause a UAF."

To fix both the UAF and the infinite loop, with netem as an hfsc child,
check explicitly in hfsc_enqueue whether the class is already in the eltree
whenever the HFSC_RSC flag is set.

[1] https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=141d34391abbb315d68556b7c67ad97885407547
[2] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L1572
[3] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L677
[4] https://elixir.bootlin.com/linux/v6.15-rc5/source/net/sched/sch_hfsc.c#L1574
[5] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/T/#u

Fixes: 37d9cf1a3c ("sched: Fix detection of empty queues in child qdiscs")
Reported-by: Savino Dicanosa <savy@syst3mfailure.io>
Reported-by: William Liu <will@willsroot.io>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Link: https://patch.msgid.link/20250522181448.1439717-2-pctammela@mojatatu.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-04 14:32:36 +02:00
arch MIPS: pm-cps: Use per-CPU variables as per-CPU, not per-core 2025-06-04 14:32:33 +02:00
block block: fix 'kmem_cache of name 'bio-108' already exists' 2025-04-10 14:29:37 +02:00
certs
crypto crypto: algif_hash - fix double free in hash_accept 2025-06-04 14:32:35 +02:00
Documentation x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 2025-06-04 14:32:32 +02:00
drivers drm/i915/gvt: fix unterminated-string-initialization warning 2025-06-04 14:32:36 +02:00
fs smb: client: Reset all search buffer pointers when releasing buffer 2025-06-04 14:32:36 +02:00
include netfilter: nf_tables: do not defer rule destruction via call_rcu 2025-06-04 14:32:36 +02:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:39:28 +02:00
ipc
kernel rcu: handle quiescent states for PREEMPT_RCU=n, PREEMPT_COUNT=y 2025-06-04 14:32:34 +02:00
lib dql: Fix dql->limit value when reset. 2025-06-04 14:32:30 +02:00
LICENSES
mm mm/page_alloc.c: avoid infinite retries caused by cpuset race 2025-06-04 14:32:36 +02:00
net net_sched: hfsc: Address reentrant enqueue adding class to eltree twice 2025-06-04 14:32:36 +02:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts kbuild: fix argument parsing in scripts/config 2025-06-04 14:32:31 +02:00
security smack: recognize ipv4 CIPSO w/o categories 2025-06-04 14:32:33 +02:00
sound ALSA: pcm: Fix race of buffer access at PCM OSS layer 2025-06-04 14:32:35 +02:00
tools bpftool: Fix readlink usage in get_fd_type 2025-06-04 14:32:34 +02:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile kbuild: Disable -Wdefault-const-init-unsafe 2025-06-04 14:32:36 +02:00
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