This is a note to let you know that I've just added the patch titled
bpf: fix 32-bit divide by zero
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: bpf-fix-32-bit-divide-by-zero.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Mon Jan 29 13:22:08 CET 2018
From: Daniel Borkmann daniel@iogearbox.net Date: Mon, 29 Jan 2018 02:49:00 +0100 Subject: bpf: fix 32-bit divide by zero To: gregkh@linuxfoundation.org Cc: ast@kernel.org, stable@vger.kernel.org, Daniel Borkmann daniel@iogearbox.net Message-ID: 0fe1fff7b023f38a11f9bebd975e29b78e5c788b.1517190207.git.daniel@iogearbox.net
From: Alexei Starovoitov ast@kernel.org
[ upstream commit 68fda450a7df51cff9e5a4d4a4d9d0d5f2589153 ]
due to some JITs doing if (src_reg == 0) check in 64-bit mode for div/mod operations mask upper 32-bits of src register before doing the check
Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT") Fixes: 7a12b5031c6b ("sparc64: Add eBPF JIT.") Reported-by: syzbot+48340bb518e88849e2e3@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/verifier.c | 18 ++++++++++++++++++ net/core/filter.c | 4 ++++ 2 files changed, 22 insertions(+)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3391,6 +3391,24 @@ static int fixup_bpf_calls(struct bpf_ve
for (i = 0; i < insn_cnt; i++, insn++) { + if (insn->code == (BPF_ALU | BPF_MOD | BPF_X) || + insn->code == (BPF_ALU | BPF_DIV | BPF_X)) { + /* due to JIT bugs clear upper 32-bits of src register + * before div/mod operation + */ + insn_buf[0] = BPF_MOV32_REG(insn->src_reg, insn->src_reg); + insn_buf[1] = *insn; + cnt = 2; + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + if (insn->code != (BPF_JMP | BPF_CALL)) continue;
--- a/net/core/filter.c +++ b/net/core/filter.c @@ -441,6 +441,10 @@ do_pass: convert_bpf_extensions(fp, &insn)) break;
+ if (fp->code == (BPF_ALU | BPF_DIV | BPF_X) || + fp->code == (BPF_ALU | BPF_MOD | BPF_X)) + *insn++ = BPF_MOV32_REG(BPF_REG_X, BPF_REG_X); + *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k); break;
Patches currently in stable-queue which might be from daniel@iogearbox.net are
queue-4.9/bpf-avoid-false-sharing-of-map-refcount-with-max_entries.patch queue-4.9/x86-bpf_jit-small-optimization-in-emit_bpf_tail_call.patch queue-4.9/bpf-reject-stores-into-ctx-via-st-and-xadd.patch queue-4.9/bpf-fix-32-bit-divide-by-zero.patch queue-4.9/bpf-fix-bpf_tail_call-x64-jit.patch queue-4.9/bpf-arsh-is-not-supported-in-32-bit-alu-thus-reject-it.patch queue-4.9/bpf-fix-divides-by-zero.patch queue-4.9/bpf-introduce-bpf_jit_always_on-config.patch