Re: [PATCH 7/9] riscv: bpf: Avoid breaking W^X

Jisheng Zhang
2021-06-11T16:30:27Z

Hi Andreas,

On Fri, 11 Jun 2021 16:10:03 +0200
Andreas Schwab <schwab@linux-m68k.org> wrote:

> On Mär 30 2021, Jisheng Zhang wrote:
>
> > From: Jisheng Zhang <jszhang@kernel.org>
> >
> > We allocate Non-executable pages, then call bpf_jit_binary_lock_ro()
> > to enable executable permission after mapping them read-only. This is
> > to prepare for STRICT_MODULE_RWX in following patch.
>
> That breaks booting with
> <https://github.com/openSUSE/kernel-source/blob/master/config/riscv64/default>.
>

Thanks for the bug report.
I reproduced an kernel panic with the defconfig on qemu, but I'm not sure whether
this is the issue you saw, I will check.

0.161959] futex hash table entries: 512 (order: 3, 32768 bytes, linear)
[ 0.167028] pinctrl core: initialized pinctrl subsystem
[ 0.190727] Unable to handle kernel paging request at virtual address ffffffff81651bd8
[ 0.191361] Oops [#1]
[ 0.191509] Modules linked in:
[ 0.191814] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.13.0-rc5-default+ #3
[ 0.192179] Hardware name: riscv-virtio,qemu (DT)
[ 0.192492] epc : __memset+0xc4/0xfc
[ 0.192712] ra : skb_flow_dissector_init+0x22/0x86
[ 0.192915] epc : ffffffff803e2700 ra : ffffffff8058f90c sp : ffffffe001a4fda0
[ 0.193221] gp : ffffffff8156d120 tp : ffffffe001a5b700 t0 : ffffffff81651b10
[ 0.193631] t1 : 0000000000000100 t2 : 00000000000003a8 s0 : ffffffe001a4fdd0
[ 0.194034] s1 : ffffffff80c9e250 a0 : ffffffff81651bd8 a1 : 0000000000000000
[ 0.194502] a2 : 000000000000003c a3 : ffffffff81651c10 a4 : 0000000000000064
[ 0.195053] a5 : ffffffff803e2700 a6 : 0000000000000040 a7 : 0000000000000002
[ 0.195436] s2 : ffffffff81651bd8 s3 : 0000000000000009 s4 : ffffffff8156e0c8
[ 0.195723] s5 : ffffffff8156e050 s6 : ffffffff80a105e0 s7 : ffffffff80a00738
[ 0.195992] s8 : ffffffff80f07be0 s9 : 0000000000000008 s10: ffffffff808000ac
[ 0.196257] s11: 0000000000000000 t3 : fffffffffffffffc t4 : 0000000000000000
[ 0.196511] t5 : 00000000000003a9 t6 : 00000000000003ff
[ 0.196714] status: 0000000000000120 badaddr: ffffffff81651bd8 cause: 000000000000000f
[ 0.197103] [<ffffffff803e2700>] __memset+0xc4/0xfc
[ 0.197408] [<ffffffff80831f58>] init_default_flow_dissectors+0x22/0x60
[ 0.197693] [<ffffffff800020fc>] do_one_initcall+0x3e/0x168
[ 0.197907] [<ffffffff80801438>] kernel_init_freeable+0x25a/0x2c6
[ 0.198157] [<ffffffff8070a8a8>] kernel_init+0x12/0x110
[ 0.198351] [<ffffffff8000333a>] ret_from_exception+0x0/0xc
[ 0.198973] Unable to handle kernel paging request at virtual address ffffffff8164d860
[ 0.199242] Oops [#2]
[ 0.199336] Modules linked in:
[ 0.199514] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G D 5.13.0-rc5-default+ #3
[ 0.199785] Hardware name: riscv-virtio,qemu (DT)
[ 0.199940] epc : _raw_spin_lock_irqsave+0x14/0x4e
[ 0.200113] ra : _extract_crng+0x58/0xac
[ 0.200264] epc : ffffffff807117ae ra : ffffffff80490774 sp : ffffffe001a4fa70
[ 0.200489] gp : ffffffff8156d120 tp : ffffffe001a5b700 t0 : ffffffff8157c0d7
[ 0.200715] t1 : ffffffff8157c0c8 t2 : 0000000000000000 s0 : ffffffe001a4fa80
[ 0.200938] s1 : ffffffff8164d818 a0 : 0000000000000022 a1 : ffffffe001a4fac8
[ 0.201166] a2 : 0000000000000010 a3 : 0000000000000001 a4 : ffffffff8164d860
[ 0.201389] a5 : 0000000000000000 a6 : c0000000ffffdfff a7 : ffffffffffffffff
[ 0.201612] s2 : ffffffff8156e1c0 s3 : ffffffe001a4fac8 s4 : ffffffff8164d860
[ 0.201836] s5 : ffffffff8156e0c8 s6 : ffffffff80a105e0 s7 : ffffffff80a00738
[ 0.202060] s8 : ffffffff80f07be0 s9 : 0000000000000008 s10: ffffffff808000ac
[ 0.202295] s11: 0000000000000000 t3 : 000000000000005b t4 : ffffffffffffffff
[ 0.202519] t5 : 00000000000003a9 t6 : ffffffe001a4f9b8
[ 0.202691] status: 0000000000000100 badaddr: ffffffff8164d860 cause: 000000000000000f
[ 0.202940] [<ffffffff807117ae>] _raw_spin_lock_irqsave+0x14/0x4e
[ 0.203326] Unable to handle kernel paging request at virtual address ffffffff8164d860
[ 0.203574] Oops [#3]
[ 0.203664] Modules linked in:
[ 0.203784] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G D 5.13.0-rc5-default+ #3
[ 0.204046] Hardware name: riscv-virtio,qemu (DT)
[ 0.204201] epc : _raw_spin_lock_irqsave+0x14/0x4e
[ 0.204371] ra : _extract_crng+0x58/0xac
[ 0.204519] epc : ffffffff807117ae ra : ffffffff80490774 sp : ffffffe001a4f740
[ 0.204819] gp : ffffffff8156d120 tp : ffffffe001a5b700 t0 : ffffffff8157c0d7
[ 0.205089] t1 : ffffffff8157c0c8 t2 : 0000000000000000 s0 : ffffffe001a4f750
[ 0.205330] s1 : ffffffff8164d818 a0 : 0000000000000102 a1 : ffffffe001a4f798
[ 0.205553] a2 : 0000000000000010 a3 : 0000000000000001 a4 : ffffffff8164d860
[ 0.205768] a5 : 0000000000000000 a6 : c0000000ffffdfff a7 : ffffffff81408a40
[ 0.205981] s2 : ffffffff8156e1c0 s3 : ffffffe001a4f798 s4 : ffffffff8164d860
[ 0.206197] s5 : ffffffff8156e0c8 s6 : ffffffff80a105e0 s7 : ffffffff80a00738
[ 0.206411] s8 : ffffffff80f07be0 s9 : 0000000000000008 s10: ffffffff808000ac
[ 0.206633] s11: 0000000000000000 t3 : 000000000000005b t4 : ffffffffffffffff
[ 0.206849] t5 : 00000000000003a9 t6 : ffffffe001a4f688