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Filename Latest commit message Latest commit date
Eric Dumazet d0b05f019f ipv6: avoid lockdep issue in fib6_del()
[ Upstream commit 843d926b003ea692468c8cc5bea1f9f58dfa8c75 ]

syzbot reported twice a lockdep issue in fib6_del() [1]
which I think is caused by net->ipv6.fib6_null_entry
having a NULL fib6_table pointer.

fib6_del() already checks for fib6_null_entry special
case, we only need to return earlier.

Bug seems to occur very rarely, I have thus chosen
a 'bug origin' that makes backports not too complex.

[1]
WARNING: suspicious RCU usage
5.9.0-rc4-syzkaller #0 Not tainted
-----------------------------
net/ipv6/ip6_fib.c:1996 suspicious rcu_dereference_protected() usage!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
4 locks held by syz-executor.5/8095:
 #0: ffffffff8a7ea708 (rtnl_mutex){+.+.}-{3:3}, at: ppp_release+0x178/0x240 drivers/net/ppp/ppp_generic.c:401
 #1: ffff88804c422dd8 (&net->ipv6.fib6_gc_lock){+.-.}-{2:2}, at: spin_trylock_bh include/linux/spinlock.h:414 [inline]
 #1: ffff88804c422dd8 (&net->ipv6.fib6_gc_lock){+.-.}-{2:2}, at: fib6_run_gc+0x21b/0x2d0 net/ipv6/ip6_fib.c:2312
 #2: ffffffff89bd6a40 (rcu_read_lock){....}-{1:2}, at: __fib6_clean_all+0x0/0x290 net/ipv6/ip6_fib.c:2613
 #3: ffff8880a82e6430 (&tb->tb6_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline]
 #3: ffff8880a82e6430 (&tb->tb6_lock){+.-.}-{2:2}, at: __fib6_clean_all+0x107/0x290 net/ipv6/ip6_fib.c:2245

stack backtrace:
CPU: 1 PID: 8095 Comm: syz-executor.5 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x198/0x1fd lib/dump_stack.c:118
 fib6_del+0x12b4/0x1630 net/ipv6/ip6_fib.c:1996
 fib6_clean_node+0x39b/0x570 net/ipv6/ip6_fib.c:2180
 fib6_walk_continue+0x4aa/0x8e0 net/ipv6/ip6_fib.c:2102
 fib6_walk+0x182/0x370 net/ipv6/ip6_fib.c:2150
 fib6_clean_tree+0xdb/0x120 net/ipv6/ip6_fib.c:2230
 __fib6_clean_all+0x120/0x290 net/ipv6/ip6_fib.c:2246
 fib6_clean_all net/ipv6/ip6_fib.c:2257 [inline]
 fib6_run_gc+0x113/0x2d0 net/ipv6/ip6_fib.c:2320
 ndisc_netdev_event+0x217/0x350 net/ipv6/ndisc.c:1805
 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83
 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2033
 call_netdevice_notifiers_extack net/core/dev.c:2045 [inline]
 call_netdevice_notifiers net/core/dev.c:2059 [inline]
 dev_close_many+0x30b/0x650 net/core/dev.c:1634
 rollback_registered_many+0x3a8/0x1210 net/core/dev.c:9261
 rollback_registered net/core/dev.c:9329 [inline]
 unregister_netdevice_queue+0x2dd/0x570 net/core/dev.c:10410
 unregister_netdevice include/linux/netdevice.h:2774 [inline]
 ppp_release+0x216/0x240 drivers/net/ppp/ppp_generic.c:403
 __fput+0x285/0x920 fs/file_table.c:281
 task_work_run+0xdd/0x190 kernel/task_work.c:141
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
 exit_to_user_mode_prepare+0x1e1/0x200 kernel/entry/common.c:190
 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:265
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 421842edea ("net/ipv6: Add fib6_null_entry")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: David Ahern <dsahern@gmail.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-26 18:03:12 +02:00
arch powerpc/dma: Fix dma_map_ops::get_required_mask 2020-09-23 12:40:46 +02:00
block block: only call sched requeue_request() for scheduled requests 2020-09-23 12:40:37 +02:00
certs
crypto crypto: af_alg - Work around empty control messages without MSG_MORE 2020-09-03 11:27:05 +02:00
Documentation affs: fix basic permission bits to actually work 2020-09-09 19:12:34 +02:00
drivers hdlc_ppp: add range checks in ppp_cp_parse_cr() 2020-09-26 18:03:12 +02:00
fs f2fs: Return EOF on unaligned end of file DIO read 2020-09-23 12:40:38 +02:00
include ipv4: Initialize flowi4_multipath_hash in data path 2020-09-26 18:03:12 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel kprobes: fix kill kprobe which has been marked as gone 2020-09-26 18:03:11 +02:00
lib kobject: Restore old behaviour of kobject_del(NULL) 2020-09-17 13:47:52 +02:00
LICENSES
mm mm/thp: fix __split_huge_pmd_locked() for migration PMD 2020-09-26 18:03:11 +02:00
net ipv6: avoid lockdep issue in fib6_del() 2020-09-26 18:03:12 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:12:37 +02:00
security Smack: prevent underflow in smk_set_cipso() 2020-08-19 08:16:16 +02:00
sound ALSA: hda/realtek - The Mic on a RedmiBook doesn't work 2020-09-23 12:40:45 +02:00
tools selftests/vm: fix display of page size in map_hugetlb 2020-09-23 12:40:46 +02:00
usr
virt KVM: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-17 13:47:54 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.67 2020-09-23 12:40:47 +02:00
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