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Davide Caratti de6d25924c net/sched: sch_ets: don't peek at classes beyond 'nbands'
when the number of DRR classes decreases, the round-robin active list can
contain elements that have already been freed in ets_qdisc_change(). As a
consequence, it's possible to see a NULL dereference crash, caused by the
attempt to call cl->qdisc->ops->peek(cl->qdisc) when cl->qdisc is NULL:

 BUG: kernel NULL pointer dereference, address: 0000000000000018
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 1 PID: 910 Comm: mausezahn Not tainted 5.16.0-rc1+ #475
 Hardware name: Red Hat KVM, BIOS 1.11.1-4.module+el8.1.0+4066+0f1aadab 04/01/2014
 RIP: 0010:ets_qdisc_dequeue+0x129/0x2c0 [sch_ets]
 Code: c5 01 41 39 ad e4 02 00 00 0f 87 18 ff ff ff 49 8b 85 c0 02 00 00 49 39 c4 0f 84 ba 00 00 00 49 8b ad c0 02 00 00 48 8b 7d 10 <48> 8b 47 18 48 8b 40 38 0f ae e8 ff d0 48 89 c3 48 85 c0 0f 84 9d
 RSP: 0000:ffffbb36c0b5fdd8 EFLAGS: 00010287
 RAX: ffff956678efed30 RBX: 0000000000000000 RCX: 0000000000000000
 RDX: 0000000000000002 RSI: ffffffff9b938dc9 RDI: 0000000000000000
 RBP: ffff956678efed30 R08: e2f3207fe360129c R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000001 R12: ffff956678efeac0
 R13: ffff956678efe800 R14: ffff956611545000 R15: ffff95667ac8f100
 FS:  00007f2aa9120740(0000) GS:ffff95667b800000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000018 CR3: 000000011070c000 CR4: 0000000000350ee0
 Call Trace:
  <TASK>
  qdisc_peek_dequeued+0x29/0x70 [sch_ets]
  tbf_dequeue+0x22/0x260 [sch_tbf]
  __qdisc_run+0x7f/0x630
  net_tx_action+0x290/0x4c0
  __do_softirq+0xee/0x4f8
  irq_exit_rcu+0xf4/0x130
  sysvec_apic_timer_interrupt+0x52/0xc0
  asm_sysvec_apic_timer_interrupt+0x12/0x20
 RIP: 0033:0x7f2aa7fc9ad4
 Code: b9 ff ff 48 8b 54 24 18 48 83 c4 08 48 89 ee 48 89 df 5b 5d e9 ed fc ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa <53> 48 83 ec 10 48 8b 05 10 64 33 00 48 8b 00 48 85 c0 0f 85 84 00
 RSP: 002b:00007ffe5d33fab8 EFLAGS: 00000202
 RAX: 0000000000000002 RBX: 0000561f72c31460 RCX: 0000561f72c31720
 RDX: 0000000000000002 RSI: 0000561f72c31722 RDI: 0000561f72c31720
 RBP: 000000000000002a R08: 00007ffe5d33fa40 R09: 0000000000000014
 R10: 0000000000000000 R11: 0000000000000246 R12: 0000561f7187e380
 R13: 0000000000000000 R14: 0000000000000000 R15: 0000561f72c31460
  </TASK>
 Modules linked in: sch_ets sch_tbf dummy rfkill iTCO_wdt intel_rapl_msr iTCO_vendor_support intel_rapl_common joydev virtio_balloon lpc_ich i2c_i801 i2c_smbus pcspkr ip_tables xfs libcrc32c crct10dif_pclmul crc32_pclmul crc32c_intel ahci libahci ghash_clmulni_intel serio_raw libata virtio_blk virtio_console virtio_net net_failover failover sunrpc dm_mirror dm_region_hash dm_log dm_mod
 CR2: 0000000000000018

Ensuring that 'alist' was never zeroed [1] was not sufficient, we need to
remove from the active list those elements that are no more SP nor DRR.

[1] https://lore.kernel.org/netdev/60d274838bf09777f0371253416e8af71360bc08.1633609148.git.dcaratti@redhat.com/

v3: fix race between ets_qdisc_change() and ets_qdisc_dequeue() delisting
    DRR classes beyond 'nbands' in ets_qdisc_change() with the qdisc lock
    acquired, thanks to Cong Wang.

v2: when a NULL qdisc is found in the DRR active list, try to dequeue skb
    from the next list item.

Reported-by: Hangbin Liu <liuhangbin@gmail.com>
Fixes: dcc68b4d80 ("net: sch_ets: Add a new Qdisc")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/7a5c496eed2d62241620bdbb83eb03fb9d571c99.1637762721.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2021-11-26 11:10:20 -08:00
arch parisc bug and warning fixes and wire up futex_waitv 2021-11-18 12:13:24 -08:00
block blk-mq: fix filesystem I/O request allocation 2021-11-12 09:31:13 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Update to zstd-1.4.10 2021-11-13 15:32:30 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2021-11-19 11:00:01 +00:00
drivers net: stmmac: Disable Tx queues when reconfiguring the interface 2021-11-26 10:38:37 -08:00
fs for-5.16-rc1-tag 2021-11-18 12:41:14 -08:00
include Merge tag 'ieee802154-for-net-2021-11-24' of git://git.kernel.org/pub/scm/linux/kernel/git/sschmidt/wpan 2021-11-24 17:02:44 -08:00
init kbuild: Fix -Wimplicit-fallthrough=5 error for GCC 5.x and 6.x 2021-11-14 18:59:49 -08:00
ipc ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL 2021-11-09 10:02:53 -08:00
kernel Networking fixes for 5.16-rc2, including fixes from bpf, mac80211. 2021-11-18 12:54:24 -08:00
lib printk fixup for 5.16 2021-11-18 10:50:45 -08:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm Revert "mm: shmem: don't truncate page if memory failure happens" 2021-11-13 12:03:03 -08:00
net net/sched: sch_ets: don't peek at classes beyond 'nbands' 2021-11-26 11:10:20 -08:00
samples samples/bpf: Fix build error due to -isystem removal 2021-11-15 20:37:20 -08:00
scripts coccinelle patches for 5.16-rc1 2021-11-13 10:45:17 -08:00
security net,lsm,selinux: revert the security_sctp_assoc_established() hook 2021-11-12 12:07:02 -05:00
sound sound fixes for 5.16-rc1 2021-11-12 12:17:30 -08:00
tools selftests: tls: test for correct proto_ops 2021-11-25 19:28:17 -08:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt Merge branch 'kvm-5.16-fixes' into kvm-master 2021-11-18 02:11:57 -05:00
.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 .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap Merge branch 'akpm' (patches from Andrew) 2021-11-09 10:11:53 -08:00
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 MAINTAINERS: Update B53 section to cover SF2 switch driver 2021-11-24 17:19:03 -08:00
Makefile Linux 5.16-rc1 2021-11-14 13:56:52 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.