From: Daniel Borkmann <daniel@iogearbox.net>
To: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
ast@kernel.org, christophe.leroy@csgroup.eu,
Hari Bathini <hbathini@linux.ibm.com>,
jniethe5@gmail.com, mpe@ellerman.id.au
Cc: songliubraving@fb.com, netdev@vger.kernel.org,
john.fastabend@gmail.com, kpsingh@kernel.org,
stable@vger.kernel.org, andrii@kernel.org, paulus@samba.org,
yhs@fb.com, bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kafai@fb.com
Subject: Re: [PATCH] powerpc/bpf: fix write protecting JIT code
Date: Tue, 26 Oct 2021 00:54:39 +0200 [thread overview]
Message-ID: <c8d7390b-c07c-75cd-e9e9-4b8f0b786cc6@iogearbox.net> (raw)
In-Reply-To: <1635142354.46h6w5c2rx.naveen@linux.ibm.com>
On 10/25/21 8:15 AM, Naveen N. Rao wrote:
> Hari Bathini wrote:
>> Running program with bpf-to-bpf function calls results in data access
>> exception (0x300) with the below call trace:
>>
>> [c000000000113f28] bpf_int_jit_compile+0x238/0x750 (unreliable)
>> [c00000000037d2f8] bpf_check+0x2008/0x2710
>> [c000000000360050] bpf_prog_load+0xb00/0x13a0
>> [c000000000361d94] __sys_bpf+0x6f4/0x27c0
>> [c000000000363f0c] sys_bpf+0x2c/0x40
>> [c000000000032434] system_call_exception+0x164/0x330
>> [c00000000000c1e8] system_call_vectored_common+0xe8/0x278
>>
>> as bpf_int_jit_compile() tries writing to write protected JIT code
>> location during the extra pass.
>>
>> Fix it by holding off write protection of JIT code until the extra
>> pass, where branch target addresses fixup happens.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 62e3d4210ac9 ("powerpc/bpf: Write protect JIT code")
>> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
>> ---
>> arch/powerpc/net/bpf_jit_comp.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Thanks for the fix!
>
> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
LGTM, I presume this fix will be routed via Michael.
BPF selftests have plenty of BPF-to-BPF calls in there, too bad this was
caught so late. :/
next prev parent reply other threads:[~2021-10-25 22:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-25 5:56 [PATCH] powerpc/bpf: fix write protecting JIT code Hari Bathini
2021-10-25 6:15 ` Naveen N. Rao
2021-10-25 22:54 ` Daniel Borkmann [this message]
2021-10-29 1:50 ` Michael Ellerman
2021-11-02 11:59 ` Naveen N. Rao
2021-11-02 13:48 ` Michael Ellerman
2021-11-02 17:34 ` Andrii Nakryiko
2021-11-02 10:12 ` Michael Ellerman
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