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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: andrii@kernel.org, bpf@vger.kernel.org, john.fastabend@gmail.com,
	kafai@fb.com, kpsingh@kernel.org, linuxppc-dev@lists.ozlabs.org,
	netdev@vger.kernel.org, paulus@samba.org, songliubraving@fb.com,
	stable@vger.kernel.org, yhs@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. :/

WARNING: multiple messages have this Message-ID (diff)
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. :/

  reply	other threads:[~2021-10-25 22:54 UTC|newest]

Thread overview: 16+ 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  5:56 ` Hari Bathini
2021-10-25  6:15 ` Naveen N. Rao
2021-10-25  6:15   ` Naveen N. Rao
2021-10-25 22:54   ` Daniel Borkmann [this message]
2021-10-25 22:54     ` Daniel Borkmann
2021-10-29  1:50     ` Michael Ellerman
2021-10-29  1:50       ` Michael Ellerman
2021-11-02 11:59       ` Naveen N. Rao
2021-11-02 11:59         ` Naveen N. Rao
2021-11-02 13:48         ` Michael Ellerman
2021-11-02 13:48           ` Michael Ellerman
2021-11-02 17:34           ` Andrii Nakryiko
2021-11-02 17:34             ` Andrii Nakryiko
2021-11-02 10:12 ` Michael Ellerman
2021-11-02 10:12   ` Michael Ellerman

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