neels has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/32421 )

Change subject: fix length check in abis_rsl_rx_rll() ......................................................................

fix length check in abis_rsl_rx_rll()

In abis_rsl_rx_rll(), we do the following header length check -- quick challenge, can you spot the two bugs hidden here?

struct abis_rsl_rll_hdr *rllh; if (msgb_l2len(msg) > sizeof(struct abis_rsl_common_hdr) + sizeof(*rllh)) msg->l3h = &rllh->data[3];

Fix these bugs:

- struct abis_rsl_common_hdr is already included as the first member of abis_rsl_rll_hdr, no need to add that. - We are going to be accessing rrlh->data[3], so we must check for at least sizeof(*rllh) + 4.

Change-Id: Ie4aee615c8c904ae8308ec0074d8bc5208137061 --- M src/osmo-bsc/abis_rsl.c 1 file changed, 26 insertions(+), 4 deletions(-)

Approvals: laforge: Looks good to me, but someone else must approve fixeria: Looks good to me, approved pespin: Looks good to me, but someone else must approve Jenkins Builder: Verified

diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c index 6370942..2fc640b 100644 --- a/src/osmo-bsc/abis_rsl.c +++ b/src/osmo-bsc/abis_rsl.c @@ -2500,8 +2500,7 @@ switch (rllh->c.msg_type) { case RSL_MT_DATA_IND: LOG_LCHAN(msg->lchan, LOGL_DEBUG, "SAPI=%u DATA INDICATION\n", sapi); - if (msgb_l2len(msg) > - sizeof(struct abis_rsl_common_hdr) + sizeof(*rllh) && + if (msgb_l2len(msg) > (sizeof(*rllh) + 3) && rllh->data[0] == RSL_IE_L3_INFO) { msg->l3h = &rllh->data[3]; return gsm0408_rcvmsg(msg, rllh->link_id); @@ -2543,8 +2542,7 @@ msg->lchan->sapis[sapi] = LCHAN_SAPI_MS; osmo_fsm_inst_dispatch(msg->lchan->fi, LCHAN_EV_RLL_ESTABLISH_IND, msg);

- if (msgb_l2len(msg) > - sizeof(struct abis_rsl_common_hdr) + sizeof(*rllh) && + if (msgb_l2len(msg) > (sizeof(*rllh) + 3) && rllh->data[0] == RSL_IE_L3_INFO) { msg->l3h = &rllh->data[3]; return gsm0408_rcvmsg(msg, rllh->link_id);