From: Kenton Groombridge concord@gentoo.org

[ Upstream commit 2663d0462eb32ae7c9b035300ab6b1523886c718 ]

req->n_channels must be set before req->channels[] can be used.

This patch fixes one of the issues encountered in [1].

[ 83.964255] UBSAN: array-index-out-of-bounds in net/mac80211/scan.c:364:4 [ 83.964258] index 0 is out of range for type 'struct ieee80211_channel *[]' [...] [ 83.964264] Call Trace: [ 83.964267] <TASK> [ 83.964269] dump_stack_lvl+0x3f/0xc0 [ 83.964274] __ubsan_handle_out_of_bounds+0xec/0x110 [ 83.964278] ieee80211_prep_hw_scan+0x2db/0x4b0 [ 83.964281] __ieee80211_start_scan+0x601/0x990 [ 83.964291] nl80211_trigger_scan+0x874/0x980 [ 83.964295] genl_family_rcv_msg_doit+0xe8/0x160 [ 83.964298] genl_rcv_msg+0x240/0x270 [...]

[1] https://bugzilla.kernel.org/show_bug.cgi?id=218810

Co-authored-by: Kees Cook keescook@chromium.org Signed-off-by: Kees Cook kees@kernel.org Signed-off-by: Kenton Groombridge concord@gentoo.org Link: https://msgid.link/20240605152218.236061-1-concord@gentoo.org Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Xiangyu Chen xiangyu.chen@windriver.com --- net/mac80211/scan.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index 62c22ff329ad..d81b49fb6458 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -357,7 +357,8 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata) struct cfg80211_scan_request *req; struct cfg80211_chan_def chandef; u8 bands_used = 0; - int i, ielen, n_chans; + int i, ielen; + u32 *n_chans; u32 flags = 0;

req = rcu_dereference_protected(local->scan_req, @@ -367,34 +368,34 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata) return false;

if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) { + local->hw_scan_req->req.n_channels = req->n_channels; + for (i = 0; i < req->n_channels; i++) { local->hw_scan_req->req.channels[i] = req->channels[i]; bands_used |= BIT(req->channels[i]->band); } - - n_chans = req->n_channels; } else { do { if (local->hw_scan_band == NUM_NL80211_BANDS) return false;

- n_chans = 0; + n_chans = &local->hw_scan_req->req.n_channels; + *n_chans = 0;

for (i = 0; i < req->n_channels; i++) { if (req->channels[i]->band != local->hw_scan_band) continue; - local->hw_scan_req->req.channels[n_chans] = + local->hw_scan_req->req.channels[(*n_chans)++] = req->channels[i]; - n_chans++; + bands_used |= BIT(req->channels[i]->band); }

local->hw_scan_band++; - } while (!n_chans); + } while (!*n_chans); }

- local->hw_scan_req->req.n_channels = n_chans; ieee80211_prepare_scan_chandef(&chandef, req->scan_width);

if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT)