bpf: Zero pad bytes preceding BPF headers
BPF headers are word-aligned when copied into the store buffer. Ensure that pad bytes following the preceding packet are cleared. Reported by: KMSAN MFC after: 1 week Sponsored by: The FreeBSD Foundation
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@ -2536,6 +2536,7 @@ catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
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void (*cpfn)(struct bpf_d *, caddr_t, u_int, void *, u_int),
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struct bintime *bt)
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{
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static char zeroes[BPF_ALIGNMENT];
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struct bpf_xhdr hdr;
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#ifndef BURN_BRIDGES
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struct bpf_hdr hdr_old;
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@ -2543,7 +2544,7 @@ catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
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struct bpf_hdr32 hdr32_old;
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#endif
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#endif
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int caplen, curlen, hdrlen, totlen;
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int caplen, curlen, hdrlen, pad, totlen;
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int do_wakeup = 0;
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int do_timestamp;
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int tstype;
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@ -2609,13 +2610,25 @@ catchpacket(struct bpf_d *d, u_char *pkt, u_int pktlen, u_int snaplen,
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ROTATE_BUFFERS(d);
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do_wakeup = 1;
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curlen = 0;
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} else if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT)
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/*
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* Immediate mode is set, or the read timeout has already
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* expired during a select call. A packet arrived, so the
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* reader should be woken up.
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*/
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do_wakeup = 1;
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} else {
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if (d->bd_immediate || d->bd_state == BPF_TIMED_OUT) {
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/*
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* Immediate mode is set, or the read timeout has
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* already expired during a select call. A packet
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* arrived, so the reader should be woken up.
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*/
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do_wakeup = 1;
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}
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pad = curlen - d->bd_slen;
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KASSERT(pad >= 0 && pad <= sizeof(zeroes),
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("%s: invalid pad byte count %d", __func__, pad));
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if (pad > 0) {
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/* Zero pad bytes. */
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bpf_append_bytes(d, d->bd_sbuf, d->bd_slen, zeroes,
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pad);
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}
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}
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caplen = totlen - hdrlen;
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tstype = d->bd_tstamp;
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do_timestamp = tstype != BPF_T_NONE;
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