This is a note to let you know that I've just added the patch titled
bpf: fix incorrect sign extension in check_alu_op()
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-incorrect-sign-extension-in-check_alu_op.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 Fri Dec 22 16:57:35 CET 2017
From: Daniel Borkmann daniel@iogearbox.net Date: Fri, 22 Dec 2017 16:29:05 +0100 Subject: bpf: fix incorrect sign extension in check_alu_op() To: gregkh@linuxfoundation.org Cc: ast@kernel.org, daniel@iogearbox.net, jannh@google.com, stable@vger.kernel.org Message-ID: 20171222152905.3455-5-daniel@iogearbox.net
From: Daniel Borkmann daniel@iogearbox.net
From: Jann Horn jannh@google.com
[ Upstream commit 95a762e2c8c942780948091f8f2a4f32fce1ac6f ]
Distinguish between BPF_ALU64|BPF_MOV|BPF_K (load 32-bit immediate, sign-extended to 64-bit) and BPF_ALU|BPF_MOV|BPF_K (load 32-bit immediate, zero-padded to 64-bit); only perform sign extension in the first case.
Starting with v4.14, this is exploitable by unprivileged users as long as the unprivileged_bpf_disabled sysctl isn't set.
Debian assigned CVE-2017-16995 for this issue.
v3: - add CVE number (Ben Hutchings)
Fixes: 484611357c19 ("bpf: allow access into map value arrays") Signed-off-by: Jann Horn jannh@google.com Acked-by: Edward Cree ecree@solarflare.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 | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1790,10 +1790,17 @@ static int check_alu_op(struct bpf_verif /* case: R = imm * remember the value we stored into this reg */ + u64 imm; + + if (BPF_CLASS(insn->code) == BPF_ALU64) + imm = insn->imm; + else + imm = (u32)insn->imm; + regs[insn->dst_reg].type = CONST_IMM; - regs[insn->dst_reg].imm = insn->imm; - regs[insn->dst_reg].max_value = insn->imm; - regs[insn->dst_reg].min_value = insn->imm; + regs[insn->dst_reg].imm = imm; + regs[insn->dst_reg].max_value = imm; + regs[insn->dst_reg].min_value = imm; }
} else if (opcode > BPF_END) {
Patches currently in stable-queue which might be from daniel@iogearbox.net are
queue-4.9/bpf-fix-branch-pruning-logic.patch queue-4.9/bpf-adjust-insn_aux_data-when-patching-insns.patch queue-4.9/bpf-fix-incorrect-sign-extension-in-check_alu_op.patch queue-4.9/bpf-reject-out-of-bounds-stack-pointer-calculation.patch