gsm48_parse_meas_rep(): set num_cell=0 if no neighbor cells are reported
Set mr->num_cell to 0 if the bits reflect 0x7, which means that no neighbor cell measurements are enclosed in the report. The code in gsm48_parse_meas_rep() acknowledges that, but nevertheless left num_cell == 7, and evaluating code commonly runs into the mistake of assuming that actually seven neighbors are being reported on, like: MEASUREMENT REPORT 0: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 1: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 2: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 3: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 4: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 5: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 6: arfcn=0 bsic=0 neigh_idx=0 rxlev=0 flags=0 There are only up to 6 slots for neighbors, the above listing actually printed 7, because num_cell == 7, which is a potential segfault. (sometimes it printed uninitialized values instead of 0) We could fix all meas rep consumers to know what num_cell == 7 means, but instead setting it to 0 trivially fixes all of them. Change-Id: Ie12210660a04f2d664ddc92e7ad7fc39ee474180
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@ -551,8 +551,11 @@ int gsm48_parse_meas_rep(struct gsm_meas_rep *rep, struct msgb *msg)
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rep->dl.sub.rx_qual = (data[2] >> 1) & 0x7;
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rep->num_cell = ((data[3] >> 6) & 0x3) | ((data[2] & 0x01) << 2);
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if (rep->num_cell < 1 || rep->num_cell > 6)
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if (rep->num_cell < 1 || rep->num_cell > 6) {
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/* There are no neighbor cell reports present. */
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rep->num_cell = 0;
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return 0;
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}
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/* an encoding nightmare in perfection */
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mrc = &rep->cell[0];
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