req->n_channels must be set before req->channels[] can be used. This patch fixes one of the issues encountered in [1].
[ 83.964252] ------------[ cut here ]------------ [ 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 *[]' [ 83.964260] CPU: 0 PID: 1695 Comm: iwd Tainted: G O T 6.8.9-gentoo-hardened1 #1 [ 83.964262] Hardware name: System76 Pangolin/Pangolin, BIOS ARB928_V00.01_T0025ASY1_ms 04/20/2023 [ 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 [ 83.964284] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964287] ? cfg80211_scan+0x149/0x250 [ 83.964291] nl80211_trigger_scan+0x874/0x980 [ 83.964295] genl_family_rcv_msg_doit+0xe8/0x160 [ 83.964298] genl_rcv_msg+0x240/0x270 [ 83.964301] ? __cfi_nl80211_trigger_scan+0x10/0x10 [ 83.964302] ? __cfi_nl80211_post_doit+0x10/0x10 [ 83.964304] ? __cfi_nl80211_pre_doit+0x10/0x10 [ 83.964307] ? __cfi_genl_rcv_msg+0x10/0x10 [ 83.964309] netlink_rcv_skb+0x102/0x130 [ 83.964312] genl_rcv+0x23/0x40 [ 83.964314] netlink_unicast+0x23b/0x340 [ 83.964316] netlink_sendmsg+0x3a9/0x450 [ 83.964319] __sys_sendto+0x3ae/0x3c0 [ 83.964324] __x64_sys_sendto+0x21/0x40 [ 83.964326] do_syscall_64+0x90/0x150 [ 83.964329] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964331] ? syscall_exit_work+0xc2/0xf0 [ 83.964333] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964335] ? syscall_exit_to_user_mode+0x74/0xa0 [ 83.964337] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964339] ? do_syscall_64+0x9c/0x150 [ 83.964340] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964342] ? syscall_exit_to_user_mode+0x74/0xa0 [ 83.964344] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964346] ? do_syscall_64+0x9c/0x150 [ 83.964347] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964349] ? do_syscall_64+0x9c/0x150 [ 83.964351] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964353] ? syscall_exit_work+0xc2/0xf0 [ 83.964354] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964356] ? syscall_exit_to_user_mode+0x74/0xa0 [ 83.964358] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964359] ? do_syscall_64+0x9c/0x150 [ 83.964361] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964362] ? do_user_addr_fault+0x488/0x620 [ 83.964366] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964367] ? srso_alias_return_thunk+0x5/0xfbef5 [ 83.964369] entry_SYSCALL_64_after_hwframe+0x55/0x5d [ 83.964372] RIP: 0033:0x6200808578d7 [ 83.964374] Code: 00 00 90 f3 0f 1e fa 41 56 55 41 89 ce 48 83 ec 28 80 3d 7b f7 0d 00 00 74 29 45 31 c9 45 31 c0 41 89 ca b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 71 48 83 c4 28 5d 41 5e c3 66 0f 1f 84 00 00 [ 83.964375] RSP: 002b:0000730c4e821530 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 83.964378] RAX: ffffffffffffffda RBX: 000006dbc456c570 RCX: 00006200808578d7 [ 83.964379] RDX: 000000000000005c RSI: 000006dbc45884f0 RDI: 0000000000000004 [ 83.964381] RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000000 [ 83.964382] R10: 0000000000000000 R11: 0000000000000246 R12: 000006dbc456c480 [ 83.964383] R13: 000006dbc456c450 R14: 0000000000000000 R15: 000006dbc456c610 [ 83.964386] </TASK> [ 83.964386] ---[ end trace ]--- [1] https://bugzilla.kernel.org/show_bug.cgi?id=218810 v3: - Fix incorrect channel copying v2: - Drop changes in cfg80211 as requested by Johannes Co-authored-by: Kees Cook <keesc...@chromium.org> Signed-off-by: Kenton Groombridge <conc...@gentoo.org> --- 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 73850312580f..56beed61d2b7 100644 --- a/net/mac80211/scan.c +++ b/net/mac80211/scan.c @@ -358,7 +358,8 @@ 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, @@ -368,34 +369,34 @@ 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); if (req->flags & NL80211_SCAN_FLAG_MIN_PREQ_CONTENT) -- 2.45.2
