From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> To: <bpf@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org> Cc: Jiri Olsa <jolsa@redhat.com>, Michael Ellerman <mpe@ellerman.id.au>, Brendan Jackman <jackmanb@google.com>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, Daniel Borkmann <daniel@iogearbox.net> Subject: [PATCH 1/2] powerpc/bpf: Fix detecting BPF atomic instructions Date: Thu, 1 Jul 2021 20:38:58 +0530 [thread overview] Message-ID: <4117b430ffaa8cd7af042496f87fd7539e4f17fd.1625145429.git.naveen.n.rao@linux.vnet.ibm.com> (raw) In-Reply-To: <cover.1625145429.git.naveen.n.rao@linux.vnet.ibm.com> Commit 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm") converted BPF_XADD to BPF_ATOMIC and added a way to distinguish instructions based on the immediate field. Existing JIT implementations were updated to check for the immediate field and to reject programs utilizing anything more than BPF_ADD (such as BPF_FETCH) in the immediate field. However, the check added to powerpc64 JIT did not look at the correct BPF instruction. Due to this, such programs would be accepted and incorrectly JIT'ed resulting in soft lockups, as seen with the atomic bounds test. Fix this by looking at the correct immediate value. Fixes: 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm") Reported-by: Jiri Olsa <jolsa@redhat.com> Tested-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- Hi Jiri, FYI: I made a small change in this patch -- using 'imm' directly, rather than insn[i].imm. I've still added your Tested-by since this shouldn't impact the fix in any way. - Naveen arch/powerpc/net/bpf_jit_comp64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 5cad5b5a7e9774..de8595880feec6 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -667,7 +667,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * * BPF_STX ATOMIC (atomic ops) */ case BPF_STX | BPF_ATOMIC | BPF_W: - if (insn->imm != BPF_ADD) { + if (imm != BPF_ADD) { pr_err_ratelimited( "eBPF filter atomic op code %02x (@%d) unsupported\n", code, i); @@ -689,7 +689,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * PPC_BCC_SHORT(COND_NE, tmp_idx); break; case BPF_STX | BPF_ATOMIC | BPF_DW: - if (insn->imm != BPF_ADD) { + if (imm != BPF_ADD) { pr_err_ratelimited( "eBPF filter atomic op code %02x (@%d) unsupported\n", code, i); -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> To: <bpf@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org> Cc: Brendan Jackman <jackmanb@google.com>, Jiri Olsa <jolsa@redhat.com>, Alexei Starovoitov <alexei.starovoitov@gmail.com>, Daniel Borkmann <daniel@iogearbox.net> Subject: [PATCH 1/2] powerpc/bpf: Fix detecting BPF atomic instructions Date: Thu, 1 Jul 2021 20:38:58 +0530 [thread overview] Message-ID: <4117b430ffaa8cd7af042496f87fd7539e4f17fd.1625145429.git.naveen.n.rao@linux.vnet.ibm.com> (raw) In-Reply-To: <cover.1625145429.git.naveen.n.rao@linux.vnet.ibm.com> Commit 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm") converted BPF_XADD to BPF_ATOMIC and added a way to distinguish instructions based on the immediate field. Existing JIT implementations were updated to check for the immediate field and to reject programs utilizing anything more than BPF_ADD (such as BPF_FETCH) in the immediate field. However, the check added to powerpc64 JIT did not look at the correct BPF instruction. Due to this, such programs would be accepted and incorrectly JIT'ed resulting in soft lockups, as seen with the atomic bounds test. Fix this by looking at the correct immediate value. Fixes: 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm") Reported-by: Jiri Olsa <jolsa@redhat.com> Tested-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- Hi Jiri, FYI: I made a small change in this patch -- using 'imm' directly, rather than insn[i].imm. I've still added your Tested-by since this shouldn't impact the fix in any way. - Naveen arch/powerpc/net/bpf_jit_comp64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 5cad5b5a7e9774..de8595880feec6 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -667,7 +667,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * * BPF_STX ATOMIC (atomic ops) */ case BPF_STX | BPF_ATOMIC | BPF_W: - if (insn->imm != BPF_ADD) { + if (imm != BPF_ADD) { pr_err_ratelimited( "eBPF filter atomic op code %02x (@%d) unsupported\n", code, i); @@ -689,7 +689,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * PPC_BCC_SHORT(COND_NE, tmp_idx); break; case BPF_STX | BPF_ATOMIC | BPF_DW: - if (insn->imm != BPF_ADD) { + if (imm != BPF_ADD) { pr_err_ratelimited( "eBPF filter atomic op code %02x (@%d) unsupported\n", code, i); -- 2.31.1
next prev parent reply other threads:[~2021-07-01 15:09 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-01 15:08 [PATCH 0/2] powerpc/bpf: Fix issue with atomic ops Naveen N. Rao 2021-07-01 15:08 ` Naveen N. Rao 2021-07-01 15:08 ` Naveen N. Rao [this message] 2021-07-01 15:08 ` [PATCH 1/2] powerpc/bpf: Fix detecting BPF atomic instructions Naveen N. Rao 2021-07-01 16:03 ` Alexei Starovoitov 2021-07-01 16:03 ` Alexei Starovoitov 2021-07-01 19:32 ` Naveen N. Rao 2021-07-01 19:32 ` Naveen N. Rao 2021-07-01 19:33 ` Alexei Starovoitov 2021-07-01 19:33 ` Alexei Starovoitov 2021-07-02 10:26 ` Jiri Olsa 2021-07-02 10:26 ` Jiri Olsa 2021-07-01 15:08 ` [PATCH 2/2] powerpc/bpf: Reject atomic ops in ppc32 JIT Naveen N. Rao 2021-07-01 15:08 ` Naveen N. Rao 2021-07-01 16:36 ` Christophe Leroy 2021-07-01 19:36 ` Naveen N. Rao 2021-07-01 19:36 ` Naveen N. Rao 2021-07-06 10:52 ` [PATCH 0/2] powerpc/bpf: Fix issue with atomic ops Michael Ellerman 2021-07-06 10:52 ` Michael Ellerman
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