[PATCH v2 1/2] scan: don't survey on external scans

James Prestwood
2024-09-05T15:27:03Z

Since surveys end up making driver calls in the kernel its not
entirely known how they are implemented or how long they will
take. For this reason the survey will be skipped if getting the
results from an external scan.

Doing this also fixes a crash caused by external scans where the
scan request pointer is not checked and dereferenced:

0x00005ffa6a0376de in get_survey_done (user_data=0x5ffa783a3f90) at src/scan.c:2059
0x0000749646a29bbd in ?? () from /usr/lib/libell.so.0
0x0000749646a243cb in ?? () from /usr/lib/libell.so.0
0x0000749646a24655 in l_main_iterate () from /usr/lib/libell.so.0
0x0000749646a24ace in l_main_run () from /usr/lib/libell.so.0
0x0000749646a263a4 in l_main_run_with_signal () from /usr/lib/libell.so.0
0x00005ffa6a00d642 in main (argc=<optimized out>, argv=<optimized out>) at src/main.c:614

Reported-by: Daniel Bond <danielbondno@gmail.com>
---
src/scan.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

v2:
* Disabled scan surveys rather than allowing a NULL scan request

diff --git a/src/scan.c b/src/scan.c
index debdeb1f..1cec9785 100644
--- a/src/scan.c
+++ b/src/scan.c
@@ -2089,9 +2089,10 @@ static void scan_get_results(struct scan_context *sc, struct scan_request *sr,
results->bss_list = l_queue_new();
results->freqs = freqs;

- if (scan_survey(results))
+ /* If there is no scan request (external scan), just get the results */
+ if (sr && scan_survey(results))
return;
- else
+ else if (sr)
l_warn("failed to start a scan survey");

get_results(results);
--
2.34.1