Harald Welte has submitted this change and it was merged.
Change subject: gsm48_parse_meas_rep(): set num_cell=0 if no neighbor cells are
reported
......................................................................
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
---
M src/libbsc/gsm_04_08_utils.c
1 file changed, 4 insertions(+), 1 deletion(-)
Approvals:
Harald Welte: Looks good to me, approved
Jenkins Builder: Verified
diff --git a/src/libbsc/gsm_04_08_utils.c b/src/libbsc/gsm_04_08_utils.c
index 3004e5d..b75b42f 100644
--- a/src/libbsc/gsm_04_08_utils.c
+++ b/src/libbsc/gsm_04_08_utils.c
@@ -551,8 +551,11 @@
rep->dl.sub.rx_qual = (data[2] >> 1) & 0x7;
rep->num_cell = ((data[3] >> 6) & 0x3) | ((data[2] & 0x01) << 2);
- if (rep->num_cell < 1 || rep->num_cell > 6)
+ if (rep->num_cell < 1 || rep->num_cell > 6) {
+ /* There are no neighbor cell reports present. */
+ rep->num_cell = 0;
return 0;
+ }
/* an encoding nightmare in perfection */
mrc = &rep->cell[0];
--
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Gerrit-MessageType: merged
Gerrit-Change-Id: Ie12210660a04f2d664ddc92e7ad7fc39ee474180
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Owner: Neels Hofmeyr <nhofm...@sysmocom.de>
Gerrit-Reviewer: Harald Welte <lafo...@gnumonks.org>
Gerrit-Reviewer: Jenkins Builder
