From 68fda450a7df51cff9e5a4d4a4d9d0d5f2589153 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 12 Jan 2018 18:59:52 -0800 Subject: bpf: fix 32-bit divide by zero 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 Signed-off-by: Daniel Borkmann --- net/core/filter.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net') diff --git a/net/core/filter.c b/net/core/filter.c index d339ef170df6..1c0eb436671f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -458,6 +458,10 @@ 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; -- cgit v1.2.3