laforge has submitted this change. ( https://gerrit.osmocom.org/c/simtrace2/+/28513 )

Change subject: host/cardem: fix integer overflow in process_do_rx_da() ......................................................................

host/cardem: fix integer overflow in process_do_rx_da()

osmo_apdu_segment_in() may return a negative number on receipt of "unknown APDU case", and that would crash simtrace2-cardem-pcsc:

msgb(0x55d2cf7aa8a0): Not enough tailroom msgb_put (allocated 920, head at 0, len 7, tailroom 1017 < want tailroom 65534) backtrace() returned 19 addresses

Whenever osmo_apdu_segment_in() fails to recognize an APDU, the communication is broken, because we don't know if we should continue transmitting or receiving. Only a successful return value by would allow us to know this. Do not crash, exit() gracefully.

Change-Id: I9e97b955a28ec886a429d744f9316e7e71be4481 Related: OS#5600 --- M host/src/simtrace2-cardem-pcsc.c 1 file changed, 7 insertions(+), 0 deletions(-)

Approvals: Jenkins Builder: Verified laforge: Looks good to me, approved

diff --git a/host/src/simtrace2-cardem-pcsc.c b/host/src/simtrace2-cardem-pcsc.c index 4820f36..374966d 100644 --- a/host/src/simtrace2-cardem-pcsc.c +++ b/host/src/simtrace2-cardem-pcsc.c @@ -167,6 +167,13 @@

rc = osmo_apdu_segment_in(&ac, data->data, data->data_len, data->flags & CEMU_DATA_F_TPDU_HDR); + if (rc < 0) { + /* At this point the communication is broken. We cannot keep running, as we + * don't know if we should continue transmitting or receiving. Only a successful + * return value by osmo_apdu_segment_in() would allow us to know this. */ + LOGCI(ci, LOGL_FATAL, "Failed to recognize APDU, terminating\n"); + exit(1); + }

if (rc & APDU_ACT_TX_CAPDU_TO_CARD) { struct msgb *tmsg = msgb_alloc(1024, "TPDU");