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Filename Latest commit message Latest commit date
Octavian Purdila e12f6013d0 net_sched: sch_sfq: don't allow 1 packet limit
[ Upstream commit 10685681bafce6febb39770f3387621bf5d67d0b ]

The current implementation does not work correctly with a limit of
1. iproute2 actually checks for this and this patch adds the check in
kernel as well.

This fixes the following syzkaller reported crash:

UBSAN: array-index-out-of-bounds in net/sched/sch_sfq.c:210:6
index 65535 is out of range for type 'struct sfq_head[128]'
CPU: 0 PID: 2569 Comm: syz-executor101 Not tainted 5.10.0-smp-DEV #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
  __dump_stack lib/dump_stack.c:79 [inline]
  dump_stack+0x125/0x19f lib/dump_stack.c:120
  ubsan_epilogue lib/ubsan.c:148 [inline]
  __ubsan_handle_out_of_bounds+0xed/0x120 lib/ubsan.c:347
  sfq_link net/sched/sch_sfq.c:210 [inline]
  sfq_dec+0x528/0x600 net/sched/sch_sfq.c:238
  sfq_dequeue+0x39b/0x9d0 net/sched/sch_sfq.c:500
  sfq_reset+0x13/0x50 net/sched/sch_sfq.c:525
  qdisc_reset+0xfe/0x510 net/sched/sch_generic.c:1026
  tbf_reset+0x3d/0x100 net/sched/sch_tbf.c:319
  qdisc_reset+0xfe/0x510 net/sched/sch_generic.c:1026
  dev_reset_queue+0x8c/0x140 net/sched/sch_generic.c:1296
  netdev_for_each_tx_queue include/linux/netdevice.h:2350 [inline]
  dev_deactivate_many+0x6dc/0xc20 net/sched/sch_generic.c:1362
  __dev_close_many+0x214/0x350 net/core/dev.c:1468
  dev_close_many+0x207/0x510 net/core/dev.c:1506
  unregister_netdevice_many+0x40f/0x16b0 net/core/dev.c:10738
  unregister_netdevice_queue+0x2be/0x310 net/core/dev.c:10695
  unregister_netdevice include/linux/netdevice.h:2893 [inline]
  __tun_detach+0x6b6/0x1600 drivers/net/tun.c:689
  tun_detach drivers/net/tun.c:705 [inline]
  tun_chr_close+0x104/0x1b0 drivers/net/tun.c:3640
  __fput+0x203/0x840 fs/file_table.c:280
  task_work_run+0x129/0x1b0 kernel/task_work.c:185
  exit_task_work include/linux/task_work.h:33 [inline]
  do_exit+0x5ce/0x2200 kernel/exit.c:931
  do_group_exit+0x144/0x310 kernel/exit.c:1046
  __do_sys_exit_group kernel/exit.c:1057 [inline]
  __se_sys_exit_group kernel/exit.c:1055 [inline]
  __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1055
 do_syscall_64+0x6c/0xd0
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fe5e7b52479
Code: Unable to access opcode bytes at RIP 0x7fe5e7b5244f.
RSP: 002b:00007ffd3c800398 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe5e7b52479
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fe5e7bcd2d0 R08: ffffffffffffffb8 R09: 0000000000000014
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe5e7bcd2d0
R13: 0000000000000000 R14: 00007fe5e7bcdd20 R15: 00007fe5e7b24270

The crash can be also be reproduced with the following (with a tc
recompiled to allow for sfq limits of 1):

tc qdisc add dev dummy0 handle 1: root tbf rate 1Kbit burst 100b lat 1s
../iproute2-6.9.0/tc/tc qdisc add dev dummy0 handle 2: parent 1:10 sfq limit 1
ifconfig dummy0 up
ping -I dummy0 -f -c2 -W0.1 8.8.8.8
sleep 1

Scenario that triggers the crash:

* the first packet is sent and queued in TBF and SFQ; qdisc qlen is 1

* TBF dequeues: it peeks from SFQ which moves the packet to the
  gso_skb list and keeps qdisc qlen set to 1. TBF is out of tokens so
  it schedules itself for later.

* the second packet is sent and TBF tries to queues it to SFQ. qdisc
  qlen is now 2 and because the SFQ limit is 1 the packet is dropped
  by SFQ. At this point qlen is 1, and all of the SFQ slots are empty,
  however q->tail is not NULL.

At this point, assuming no more packets are queued, when sch_dequeue
runs again it will decrement the qlen for the current empty slot
causing an underflow and the subsequent out of bounds access.

Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Octavian Purdila <tavip@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241204030520.2084663-2-tavip@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-08-28 16:21:17 +02:00
arch x86/mm: Disable hugetlb page table sharing on 32-bit 2025-07-17 18:25:06 +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 scsi: ufs: core: Fix spelling of a sysfs attribute name 2025-07-17 18:24:58 +02:00
drivers power: supply: bq24190: Fix use after free bug in bq24190_remove due to race condition 2025-08-28 16:21:17 +02:00
fs isofs: Verify inode mode when loading from disk 2025-08-28 16:21:15 +02:00
include drm/sched: Increment job count before swapping tail spsc queue 2025-07-17 18:25:03 +02:00
init bpfilter: match bit size of bpfilter_umh to that of the kernel 2025-07-17 18:24:51 +02:00
ipc ipc: fix to protect IPCS lookups using RCU 2025-06-27 11:02:52 +01:00
kernel perf: Fix sample vs do_exit() 2025-06-27 11:02:58 +01:00
lib lib: test_objagg: Set error message in check_expect_hints_stats() 2025-07-17 18:24:56 +02:00
LICENSES
mm mm/huge_memory: fix dereferencing invalid pmd migration entry 2025-06-27 11:02:58 +01:00
net net_sched: sch_sfq: don't allow 1 packet limit 2025-08-28 16:21:17 +02:00
samples
scripts kbuild: use -MMD instead of -MD to exclude system headers from dependency 2025-07-17 18:24:51 +02:00
security selinux: fix selinux_xfrm_alloc_user() to set correct ctx_len 2025-06-27 11:02:56 +01:00
sound ASoC: fsl_sai: Force a software reset when starting in consumer mode 2025-08-28 16:21:16 +02:00
tools perf record: Fix incorrect --user-regs comments 2025-06-27 11:02:48 +01:00
usr kbuild: hdrcheck: fix cross build with clang 2025-07-17 18:24:51 +02:00
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS platform: Add Surface platform directory 2025-06-27 11:02:56 +01:00
Makefile Linux 5.4.296 2025-07-17 18:25:06 +02:00
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