From: syzbot <syzbot+2e3bf0bd49acd9b21d4b@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, nenkov2004@gmail.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [block?] BUG: unable to handle kernel paging request in blk_mq_complete_request_remote
Date: Tue, 10 Nov 2026 13:49:04 -0800 [thread overview]
Message-ID: <6af39150.6ea51c61.3838e6.0017.GAE@google.com> (raw)
In-Reply-To: <CAO7_G+wHdgLNKCbCGypfCUbp23eB+fdp-OmFRkn6WNnRTCfTkg@mail.gmail.com>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: null-ptr-deref Write in fib_insert_alias
==================================================================
BUG: KASAN: null-ptr-deref in hlist_add_before_rcu include/linux/rculist.h:744 [inline]
BUG: KASAN: null-ptr-deref in fib_insert_alias+0xb0/0xb08 net/ipv4/fib_trie.c:1160
Write of size 8 at addr 0000000000000000 by task syz-executor/5244
CPU: 1 UID: 0 PID: 5244 Comm: syz-executor Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
print_report+0x58/0x84 mm/kasan/report.c:485
kasan_report+0x8c/0xc4 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x17c/0x1ac mm/kasan/generic.c:200
__kasan_check_write+0x20/0x30 mm/kasan/shadow.c:37
hlist_add_before_rcu include/linux/rculist.h:744 [inline]
fib_insert_alias+0xb0/0xb08 net/ipv4/fib_trie.c:1160
fib_table_insert+0x5dc/0x12bc net/ipv4/fib_trie.c:1352
fib_magic+0x26c/0x344 net/ipv4/fib_frontend.c:1147
fib_add_ifaddr+0x2e0/0x500 net/ipv4/fib_frontend.c:1184
fib_netdev_event+0x35c/0x49c net/ipv4/fib_frontend.c:1529
notifier_call_chain+0x1a4/0x4cc kernel/notifier.c:86
raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:558
call_netdevice_notifiers_info+0xb8/0x120 net/core/dev.c:2313
call_netdevice_notifiers_extack net/core/dev.c:2351 [inline]
call_netdevice_notifiers net/core/dev.c:2365 [inline]
__dev_notify_flags+0x288/0x438 net/core/dev.c:10051
netif_change_flags+0xd0/0x15c net/core/dev.c:10080
do_setlink+0xc28/0x32d4 net/core/rtnetlink.c:3294
rtnl_changelink net/core/rtnetlink.c:3942 [inline]
__rtnl_newlink net/core/rtnetlink.c:4113 [inline]
rtnl_newlink+0xf48/0x1390 net/core/rtnetlink.c:4252
rtnetlink_rcv_msg+0x66c/0x9bc net/core/rtnetlink.c:7169
netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2584
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:7196
netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
netlink_unicast+0x73c/0x934 net/netlink/af_netlink.c:1361
netlink_sendmsg+0x670/0x98c net/netlink/af_netlink.c:1920
sock_sendmsg_nosec net/socket.c:800 [inline]
__sock_sendmsg+0xc8/0x188 net/socket.c:818
__sys_sendto+0x250/0x328 net/socket.c:2283
__do_sys_sendto net/socket.c:2290 [inline]
__se_sys_sendto net/socket.c:2286 [inline]
__arm64_sys_sendto+0xec/0x10c net/socket.c:2286
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:797
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:816
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606
==================================================================
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x0000000096000044
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000
CM = 0, WnR = 1, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001173dd000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000044 [#1] SMP
Modules linked in:
CPU: 1 UID: 0 PID: 5244 Comm: syz-executor Tainted: G B syzkaller #0 PREEMPT
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/06/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : hlist_add_before_rcu include/linux/rculist.h:744 [inline]
pc : fib_insert_alias+0xb0/0xb08 net/ipv4/fib_trie.c:1160
lr : hlist_add_before_rcu include/linux/rculist.h:744 [inline]
lr : fib_insert_alias+0xb0/0xb08 net/ipv4/fib_trie.c:1160
sp : ffff800096b86750
x29: ffff800096b86780 x28: ffff0000c8fb8528 x27: ffff0000eb35fc20
x26: dfff800000000000 x25: 0000000000000018 x24: ffff0000c8fb8210
x23: ffff0000dcc87660 x22: 0000000000000000 x21: ffff0000c8fb8528
x20: ffff0000c8fb8218 x19: 1fffe000191f7043 x18: 0000000000000000
x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d
x14: 00000000000006f9 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: ffff70001161f92d x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : ffff8000804a0c38
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff80008030c9a8
x2 : 0000000000000000 x1 : ffff0000c1fb1d80 x0 : 0000000000000000
Call trace:
hlist_add_before_rcu include/linux/rculist.h:744 [inline] (P)
fib_insert_alias+0xb0/0xb08 net/ipv4/fib_trie.c:1160 (P)
fib_table_insert+0x5dc/0x12bc net/ipv4/fib_trie.c:1352
fib_magic+0x26c/0x344 net/ipv4/fib_frontend.c:1147
fib_add_ifaddr+0x2e0/0x500 net/ipv4/fib_frontend.c:1184
fib_netdev_event+0x35c/0x49c net/ipv4/fib_frontend.c:1529
notifier_call_chain+0x1a4/0x4cc kernel/notifier.c:86
raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:558
call_netdevice_notifiers_info+0xb8/0x120 net/core/dev.c:2313
call_netdevice_notifiers_extack net/core/dev.c:2351 [inline]
call_netdevice_notifiers net/core/dev.c:2365 [inline]
__dev_notify_flags+0x288/0x438 net/core/dev.c:10051
netif_change_flags+0xd0/0x15c net/core/dev.c:10080
do_setlink+0xc28/0x32d4 net/core/rtnetlink.c:3294
rtnl_changelink net/core/rtnetlink.c:3942 [inline]
__rtnl_newlink net/core/rtnetlink.c:4113 [inline]
rtnl_newlink+0xf48/0x1390 net/core/rtnetlink.c:4252
rtnetlink_rcv_msg+0x66c/0x9bc net/core/rtnetlink.c:7169
netlink_rcv_skb+0x238/0x414 net/netlink/af_netlink.c:2584
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:7196
netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
netlink_unicast+0x73c/0x934 net/netlink/af_netlink.c:1361
netlink_sendmsg+0x670/0x98c net/netlink/af_netlink.c:1920
sock_sendmsg_nosec net/socket.c:800 [inline]
__sock_sendmsg+0xc8/0x188 net/socket.c:818
__sys_sendto+0x250/0x328 net/socket.c:2283
__do_sys_sendto net/socket.c:2290 [inline]
__se_sys_sendto net/socket.c:2286 [inline]
__arm64_sys_sendto+0xec/0x10c net/socket.c:2286
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x60/0x1d8 arch/arm64/kernel/entry-common.c:797
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:816
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:606
Code: aa1603e0 52800101 f90002b8 96d8b07a (c89ffed5)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: aa1603e0 mov x0, x22
4: 52800101 mov w1, #0x8 // #8
8: f90002b8 str x24, [x21]
c: 96d8b07a bl 0xfffffffffb62c1f4
* 10: c89ffed5 stlr x21, [x22] <-- trapping instruction
Tested on:
commit: 067c5c24 Merge tag 'page_alloc-for-7.4-rc2' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12c7b1fd580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c06331d9bb9c8204
dashboard link: https://syzkaller.appspot.com/bug?extid=2e3bf0bd49acd9b21d4b
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
userspace arch: arm64
patch: https://syzkaller.appspot.com/x/patch.diff?x=16dccebe580000
next parent reply other threads:[~2026-11-10 21:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAO7_G+wHdgLNKCbCGypfCUbp23eB+fdp-OmFRkn6WNnRTCfTkg@mail.gmail.com>
2026-11-10 21:49 ` syzbot [this message]
2026-11-11 1:13 ` Hristos Nenkov
[not found] <CAO7_G+w-YoXKa7uTPZgu8JK=zvVOigzOjewNu=kZMZvGTxh8Jw@mail.gmail.com>
2026-11-10 22:09 ` syzbot
[not found] <CAO7_G+y3L5-N_-01cHPEbyvEob5mwgDCN2JgEHJoALzcptMX8A@mail.gmail.com>
2026-11-10 22:08 ` syzbot
2026-08-27 10:07 syzbot
2026-10-07 11:18 ` syzbot
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