Re: [syzbot] bpf-next boot error: KASAN: null-ptr-deref Write in register_btf_kfunc_id_set

From: Alexei Starovoitov
Date: Wed Mar 23 2022 - 15:54:21 EST


Kumar,

please take a look.

Thanks!

On Wed, Mar 23, 2022 at 12:14 PM syzbot
<syzbot+12babd2d45fac8bfff7d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: a8fee96202e2 libbpf: Avoid NULL deref when initializing ma..
> git tree: bpf-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1686180b700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=820db791969fe863
> dashboard link: https://syzkaller.appspot.com/bug?extid=12babd2d45fac8bfff7d
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+12babd2d45fac8bfff7d@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> usbcore: registered new interface driver snd-usb-audio
> usbcore: registered new interface driver snd-ua101
> usbcore: registered new interface driver snd-usb-usx2y
> usbcore: registered new interface driver snd-usb-us122l
> usbcore: registered new interface driver snd-usb-caiaq
> usbcore: registered new interface driver snd-usb-6fire
> usbcore: registered new interface driver snd-usb-hiface
> usbcore: registered new interface driver snd-bcd2000
> usbcore: registered new interface driver snd_usb_pod
> usbcore: registered new interface driver snd_usb_podhd
> usbcore: registered new interface driver snd_usb_toneport
> usbcore: registered new interface driver snd_usb_variax
> drop_monitor: Initializing network drop monitor service
> NET: Registered PF_LLC protocol family
> GACT probability on
> Mirror/redirect action on
> Simple TC action Loaded
> netem: version 1.3
> u32 classifier
> Performance counters on
> input device check on
> Actions configured
> nf_conntrack_irc: failed to register helpers
> nf_conntrack_sane: failed to register helpers
> nf_conntrack_sip: failed to register helpers
> xt_time: kernel timezone is -0000
> IPVS: Registered protocols (TCP, UDP, SCTP, AH, ESP)
> IPVS: Connection hash table configured (size=4096, memory=64Kbytes)
> IPVS: ipvs loaded.
> IPVS: [rr] scheduler registered.
> IPVS: [wrr] scheduler registered.
> IPVS: [lc] scheduler registered.
> IPVS: [wlc] scheduler registered.
> IPVS: [fo] scheduler registered.
> IPVS: [ovf] scheduler registered.
> IPVS: [lblc] scheduler registered.
> IPVS: [lblcr] scheduler registered.
> IPVS: [dh] scheduler registered.
> IPVS: [sh] scheduler registered.
> IPVS: [mh] scheduler registered.
> IPVS: [sed] scheduler registered.
> IPVS: [nq] scheduler registered.
> IPVS: [twos] scheduler registered.
> IPVS: [sip] pe registered.
> ipip: IPv4 and MPLS over IPv4 tunneling driver
> gre: GRE over IPv4 demultiplexor driver
> ip_gre: GRE over IPv4 tunneling driver
> IPv4 over IPsec tunneling driver
> ipt_CLUSTERIP: ClusterIP Version 0.8 loaded successfully
> ==================================================================
> BUG: KASAN: null-ptr-deref in instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
> BUG: KASAN: null-ptr-deref in atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
> BUG: KASAN: null-ptr-deref in __refcount_add include/linux/refcount.h:193 [inline]
> BUG: KASAN: null-ptr-deref in __refcount_inc include/linux/refcount.h:250 [inline]
> BUG: KASAN: null-ptr-deref in refcount_inc include/linux/refcount.h:267 [inline]
> BUG: KASAN: null-ptr-deref in btf_get kernel/bpf/btf.c:1636 [inline]
> BUG: KASAN: null-ptr-deref in btf_get_module_btf kernel/bpf/btf.c:6588 [inline]
> BUG: KASAN: null-ptr-deref in register_btf_kfunc_id_set+0x99/0x8b0 kernel/bpf/btf.c:6812
> Write of size 4 at addr 0000000000000054 by task swapper/0/1
>
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc6-syzkaller-02045-ga8fee96202e2 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> __kasan_report mm/kasan/report.c:446 [inline]
> kasan_report.cold+0x66/0xdf mm/kasan/report.c:459
> check_region_inline mm/kasan/generic.c:183 [inline]
> kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
> instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
> atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
> __refcount_add include/linux/refcount.h:193 [inline]
> __refcount_inc include/linux/refcount.h:250 [inline]
> refcount_inc include/linux/refcount.h:267 [inline]
> btf_get kernel/bpf/btf.c:1636 [inline]
> btf_get_module_btf kernel/bpf/btf.c:6588 [inline]
> register_btf_kfunc_id_set+0x99/0x8b0 kernel/bpf/btf.c:6812
> bbr_register+0x18/0x48 net/ipv4/tcp_bbr.c:1183
> do_one_initcall+0x103/0x650 init/main.c:1302
> do_initcall_level init/main.c:1375 [inline]
> do_initcalls init/main.c:1391 [inline]
> do_basic_setup init/main.c:1410 [inline]
> kernel_init_freeable+0x6b1/0x73a init/main.c:1615
> kernel_init+0x1a/0x1d0 init/main.c:1504
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
> ==================================================================
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G B 5.17.0-rc6-syzkaller-02045-ga8fee96202e2 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:88 [inline]
> dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
> panic+0x2b0/0x6dd kernel/panic.c:233
> end_report.cold+0x63/0x6f mm/kasan/report.c:128
> __kasan_report mm/kasan/report.c:449 [inline]
> kasan_report.cold+0x71/0xdf mm/kasan/report.c:459
> check_region_inline mm/kasan/generic.c:183 [inline]
> kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
> instrument_atomic_read_write include/linux/instrumented.h:101 [inline]
> atomic_fetch_add_relaxed include/linux/atomic/atomic-instrumented.h:116 [inline]
> __refcount_add include/linux/refcount.h:193 [inline]
> __refcount_inc include/linux/refcount.h:250 [inline]
> refcount_inc include/linux/refcount.h:267 [inline]
> btf_get kernel/bpf/btf.c:1636 [inline]
> btf_get_module_btf kernel/bpf/btf.c:6588 [inline]
> register_btf_kfunc_id_set+0x99/0x8b0 kernel/bpf/btf.c:6812
> bbr_register+0x18/0x48 net/ipv4/tcp_bbr.c:1183
> do_one_initcall+0x103/0x650 init/main.c:1302
> do_initcall_level init/main.c:1375 [inline]
> do_initcalls init/main.c:1391 [inline]
> do_basic_setup init/main.c:1410 [inline]
> kernel_init_freeable+0x6b1/0x73a init/main.c:1615
> kernel_init+0x1a/0x1d0 init/main.c:1504
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> </TASK>
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
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>
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