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Eric Dumazet 2174a08db8 sch_netem: acquire qdisc lock in netem_change()
syzbot managed to trigger a divide error [1] in netem.

It could happen if q->rate changes while netem_enqueue()
is running, since q->rate is read twice.

It turns out netem_change() always lacked proper synchronization.

[1]
divide error: 0000 [#1] SMP KASAN
CPU: 1 PID: 7867 Comm: syz-executor.1 Not tainted 6.1.30-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
RIP: 0010:div64_u64 include/linux/math64.h:69 [inline]
RIP: 0010:packet_time_ns net/sched/sch_netem.c:357 [inline]
RIP: 0010:netem_enqueue+0x2067/0x36d0 net/sched/sch_netem.c:576
Code: 89 e2 48 69 da 00 ca 9a 3b 42 80 3c 28 00 4c 8b a4 24 88 00 00 00 74 0d 4c 89 e7 e8 c3 4f 3b fd 48 8b 4c 24 18 48 89 d8 31 d2 <49> f7 34 24 49 01 c7 4c 8b 64 24 48 4d 01 f7 4c 89 e3 48 c1 eb 03
RSP: 0018:ffffc9000dccea60 EFLAGS: 00010246
RAX: 000001a442624200 RBX: 000001a442624200 RCX: ffff888108a4f000
RDX: 0000000000000000 RSI: 000000000000070d RDI: 000000000000070d
RBP: ffffc9000dcceb90 R08: ffffffff849c5e26 R09: fffffbfff10e1297
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888108a4f358
R13: dffffc0000000000 R14: 0000001a8cd9a7ec R15: 0000000000000000
FS: 00007fa73fe18700(0000) GS:ffff8881f6b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa73fdf7718 CR3: 000000011d36e000 CR4: 0000000000350ee0
Call Trace:
<TASK>
[<ffffffff84714385>] __dev_xmit_skb net/core/dev.c:3931 [inline]
[<ffffffff84714385>] __dev_queue_xmit+0xcf5/0x3370 net/core/dev.c:4290
[<ffffffff84d22df2>] dev_queue_xmit include/linux/netdevice.h:3030 [inline]
[<ffffffff84d22df2>] neigh_hh_output include/net/neighbour.h:531 [inline]
[<ffffffff84d22df2>] neigh_output include/net/neighbour.h:545 [inline]
[<ffffffff84d22df2>] ip_finish_output2+0xb92/0x10d0 net/ipv4/ip_output.c:235
[<ffffffff84d21e63>] __ip_finish_output+0xc3/0x2b0
[<ffffffff84d10a81>] ip_finish_output+0x31/0x2a0 net/ipv4/ip_output.c:323
[<ffffffff84d10f14>] NF_HOOK_COND include/linux/netfilter.h:298 [inline]
[<ffffffff84d10f14>] ip_output+0x224/0x2a0 net/ipv4/ip_output.c:437
[<ffffffff84d123b5>] dst_output include/net/dst.h:444 [inline]
[<ffffffff84d123b5>] ip_local_out net/ipv4/ip_output.c:127 [inline]
[<ffffffff84d123b5>] __ip_queue_xmit+0x1425/0x2000 net/ipv4/ip_output.c:542
[<ffffffff84d12fdc>] ip_queue_xmit+0x4c/0x70 net/ipv4/ip_output.c:556

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230620184425.1179809-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2023-06-22 10:58:52 +02:00
arch bpf-for-netdev 2023-06-21 13:59:46 -07:00
block blk-mq: fix blk_mq_hw_ctx active request accounting 2023-06-03 17:20:00 -06:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-02 15:36:23 +02:00
Documentation Devicetree fixes for v6.4, part 3: 2023-06-13 10:27:56 -07:00
drivers Revert "net: phy: dp83867: perform soft reset and retain established link" 2023-06-20 20:20:22 -07:00
fs Fix two regressions in ext4, one report by syzkaller[1], and reported by 2023-06-15 15:40:58 -07:00
include ipsec-2023-06-20 2023-06-20 13:33:50 +01:00
init Objtool changes for v6.4: 2023-04-28 14:02:54 -07:00
io_uring io_uring/io-wq: don't clear PF_IO_WORKER on exit 2023-06-12 11:16:09 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf-for-netdev 2023-06-21 13:59:46 -07:00
lib 19 hotfixes. 14 are cc:stable and the remainder address issues which were 2023-06-12 16:14:34 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm 19 hotfixes. 14 are cc:stable and the remainder address issues which were 2023-06-12 16:14:34 -07:00
net sch_netem: acquire qdisc lock in netem_change() 2023-06-22 10:58:52 +02:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples samples/bpf: Drop unnecessary fallthrough 2023-05-16 19:44:05 +02:00
scripts Locking changes in v6.4: 2023-05-05 12:56:55 -07:00
security selinux: don't use make's grouped targets feature yet 2023-06-01 13:56:13 -04:00
sound ALSA: hda/realtek: Enable 4 amplifiers instead of 2 on a HP platform 2023-06-06 17:44:24 +02:00
tools selftests: forwarding: Fix race condition in mirror installation 2023-06-22 10:03:07 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Fix vcpu_array[0] races 2023-05-19 13:56:26 -04:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entry for John Keeping 2023-06-12 11:31:52 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS MAINTAINERS: add me as maintainer of MEDIATEK SWITCH DRIVER 2023-06-20 09:40:26 +01:00
Makefile Linux 6.4-rc6 2023-06-11 14:35:30 -07:00
README

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There are various text files in the Documentation/ subdirectory,
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