From 92ecbb3ac6f3fe8ae9edf3226c76aa17b6800699 Mon Sep 17 00:00:00 2001 From: Dmitry Antipov Date: Fri, 17 May 2024 18:33:32 +0300 Subject: [PATCH] wifi: mac80211: fix UBSAN noise in ieee80211_prep_hw_scan() When testing the previous patch with CONFIG_UBSAN_BOUNDS, I've noticed the following: UBSAN: array-index-out-of-bounds in net/mac80211/scan.c:372:4 index 0 is out of range for type 'struct ieee80211_channel *[]' CPU: 0 PID: 1435 Comm: wpa_supplicant Not tainted 6.9.0+ #1 Hardware name: LENOVO 20UN005QRT/20UN005QRT <...BIOS details...> Call Trace: dump_stack_lvl+0x2d/0x90 __ubsan_handle_out_of_bounds+0xe7/0x140 ? timerqueue_add+0x98/0xb0 ieee80211_prep_hw_scan+0x2db/0x480 [mac80211] ? __kmalloc+0xe1/0x470 __ieee80211_start_scan+0x541/0x760 [mac80211] rdev_scan+0x1f/0xe0 [cfg80211] nl80211_trigger_scan+0x9b6/0xae0 [cfg80211] ... Since '__ieee80211_start_scan()' leaves 'hw_scan_req->req.n_channels' uninitialized, actual boundaries of 'hw_scan_req->req.channels' can't be checked in 'ieee80211_prep_hw_scan()'. Although an initialization of 'hw_scan_req->req.n_channels' introduces some confusion around allocated vs. used VLA members, this shouldn't be a problem since everything is correctly adjusted soon in 'ieee80211_prep_hw_scan()'. Cleanup 'kmalloc()' math in '__ieee80211_start_scan()' by using the convenient 'struct_size()' as well. Signed-off-by: Dmitry Antipov Link: https://msgid.link/20240517153332.18271-2-dmantipov@yandex.ru [improve (imho) indentation a bit] Signed-off-by: Johannes Berg --- net/mac80211/scan.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c index 3da1c5c45035..8ecc4b710b0e 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -744,15 +744,21 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata, local->hw_scan_ies_bufsize *= n_bands; } - local->hw_scan_req = kmalloc( - sizeof(*local->hw_scan_req) + - req->n_channels * sizeof(req->channels[0]) + - local->hw_scan_ies_bufsize, GFP_KERNEL); + local->hw_scan_req = kmalloc(struct_size(local->hw_scan_req, + req.channels, + req->n_channels) + + local->hw_scan_ies_bufsize, + GFP_KERNEL); if (!local->hw_scan_req) return -ENOMEM; local->hw_scan_req->req.ssids = req->ssids; local->hw_scan_req->req.n_ssids = req->n_ssids; + /* None of the channels are actually set + * up but let UBSAN know the boundaries. + */ + local->hw_scan_req->req.n_channels = req->n_channels; + ies = (u8 *)local->hw_scan_req + sizeof(*local->hw_scan_req) + req->n_channels * sizeof(req->channels[0]);