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From: Martin KaFai Lau <kafai@fb.com>
To: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	David Miller <davem@davemloft.net>, <kernel-team@fb.com>
Subject: [PATCH v3 bpf-next 1/3] bpf: Account for insn->off when doing bpf_probe_read_kernel
Date: Wed, 6 Nov 2019 17:46:40 -0800	[thread overview]
Message-ID: <20191107014640.384083-1-kafai@fb.com> (raw)
In-Reply-To: <20191107014639.384014-1-kafai@fb.com>

In the bpf interpreter mode, bpf_probe_read_kernel is used to read
from PTR_TO_BTF_ID's kernel object.  It currently missed considering
the insn->off.  This patch fixes it.

Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 kernel/bpf/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 97e37d82a1cc..c1fde0303280 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1569,7 +1569,7 @@ static u64 __no_fgcse ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn, u6
 #undef LDST
 #define LDX_PROBE(SIZEOP, SIZE)							\
 	LDX_PROBE_MEM_##SIZEOP:							\
-		bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) SRC);	\
+		bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off));	\
 		CONT;
 	LDX_PROBE(B,  1)
 	LDX_PROBE(H,  2)
-- 
2.17.1


  reply	other threads:[~2019-11-07  1:46 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-07  1:46 [PATCH v3 bpf-next 0/3] bpf: Add array support to btf_struct_access Martin KaFai Lau
2019-11-07  1:46 ` Martin KaFai Lau [this message]
2019-11-07  2:45   ` [PATCH v3 bpf-next 1/3] bpf: Account for insn->off when doing bpf_probe_read_kernel Andrii Nakryiko
2019-11-07  5:57   ` Alexei Starovoitov
2019-11-07  1:46 ` [PATCH v3 bpf-next 2/3] bpf: Add array support to btf_struct_access Martin KaFai Lau
2019-11-07  2:41   ` Andrii Nakryiko
2019-11-07 17:22     ` Martin Lau
2019-11-07 17:26       ` Andrii Nakryiko
2019-11-07  1:46 ` [PATCH v3 bpf-next 3/3] bpf: Add cb access in kfree_skb test Martin KaFai Lau
2019-11-07  2:50   ` Andrii Nakryiko
2019-11-07 17:29     ` Martin Lau

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