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Marco Elver c8b23e12a7 bpf_lru_list: Read double-checked variable once without lock
[ Upstream commit 6df8fb83301d68ea0a0c0e1cbcc790fcc333ed12 ]

For double-checked locking in bpf_common_lru_push_free(), node->type is
read outside the critical section and then re-checked under the lock.
However, concurrent writes to node->type result in data races.

For example, the following concurrent access was observed by KCSAN:

  write to 0xffff88801521bc22 of 1 bytes by task 10038 on cpu 1:
   __bpf_lru_node_move_in        kernel/bpf/bpf_lru_list.c:91
   __local_list_flush            kernel/bpf/bpf_lru_list.c:298
   ...
  read to 0xffff88801521bc22 of 1 bytes by task 10043 on cpu 0:
   bpf_common_lru_push_free      kernel/bpf/bpf_lru_list.c:507
   bpf_lru_push_free             kernel/bpf/bpf_lru_list.c:555
   ...

Fix the data races where node->type is read outside the critical section
(for double-checked locking) by marking the access with READ_ONCE() as
well as ensuring the variable is only accessed once.

Fixes: 3a08c2fd76 ("bpf: LRU List")
Reported-by: syzbot+3536db46dfa58c573458@syzkaller.appspotmail.com
Reported-by: syzbot+516acdb03d3e27d91bcd@syzkaller.appspotmail.com
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210209112701.3341724-1-elver@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-03-04 11:37:29 +01:00
arch ARM: at91: use proper asm syntax in pm_suspend 2021-03-04 11:37:28 +01:00
block bfq: Avoid false bfq queue merging 2021-03-04 11:37:18 +01:00
certs
crypto crypto: xor - Fix divide error in do_xor_speed() 2021-01-27 11:54:52 +01:00
Documentation scsi: libsas: docs: Remove notify_ha_event() 2021-03-04 11:37:17 +01:00
drivers iwlwifi: mvm: don't check if CSA event is running before removing 2021-03-04 11:37:29 +01:00
fs debugfs: do not attempt to create a new file before the filesystem is initalized 2021-03-04 11:37:17 +01:00
include ACPICA: Fix exception code class checks 2021-03-04 11:37:24 +01:00
init fgraph: Initialize tracing_graph_pause at task creation 2021-02-10 09:29:16 +01:00
ipc
kernel bpf_lru_list: Read double-checked variable once without lock 2021-03-04 11:37:29 +01:00
lib udp: fix skb_copy_and_csum_datagram with odd segment sizes 2021-02-17 11:02:28 +01:00
LICENSES
mm mm: provide a saner PTE walking API for modules 2021-02-26 10:13:01 +01:00
net Bluetooth: Put HCI device if inquiry procedure interrupts 2021-03-04 11:37:25 +01:00
samples samples/bpf: Fix possible hang in xdpsock with multiple threads 2020-12-30 11:53:49 +01:00
scripts scripts/recordmcount.pl: support big endian for ARCH sh 2021-02-26 10:13:02 +01:00
security cap: fix conversions on getxattr 2021-02-17 11:02:22 +01:00
sound ALSA: pcm: Don't call sync_stop if it hasn't been stopped 2021-03-04 11:37:19 +01:00
tools selftests: txtimestamp: fix compilation issue 2021-02-17 11:02:26 +01:00
usr
virt KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() 2021-02-26 10:13:01 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
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.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
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MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-12-10 15:30:13 -08:00
Makefile Linux 5.10.19 2021-02-26 10:14:35 +01:00
README

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