netdev - Re: [PATCH v5.10.y v5.4.y] wifi: mac80211: Avoid address calculations via out of bounds array indexing

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Message-ID: <CAH+zgeGs7Tk+3sP=Bn4=11i5pH3xjZquy-x1ykTXMBE8HcOtew@mail.gmail.com>
Date: Thu, 5 Dec 2024 11:41:45 +0530
From: Hardik Gohil <hgohil@...sta.com>
To: Greg KH <gregkh@...uxfoundation.org>
Cc: stable@...r.kernel.org, netdev@...r.kernel.org, 
	Kenton Groombridge <concord@...too.org>, Kees Cook <kees@...nel.org>, 
	Johannes Berg <johannes.berg@...el.com>, Xiangyu Chen <xiangyu.chen@...driver.com>, 
	Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH v5.10.y v5.4.y] wifi: mac80211: Avoid address calculations
 via out of bounds array indexing

From: Kenton Groombridge <concord@...too.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@...omium.org>
Signed-off-by: Kees Cook <kees@...nel.org>
Signed-off-by: Kenton Groombridge <concord@...too.org>
Link: https://msgid.link/20240605152218.236061-1-concord@gentoo.org
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
[Xiangyu: Modified to apply on 6.1.y and 6.6.y]
Signed-off-by: Xiangyu Chen <xiangyu.chen@...driver.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
Signed-off-by: Hardik Gohil <hgohil@...sta.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 be5d02c..bcbbb9f 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -351,7 +351,8 @@ 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,
@@ -361,34 +362,34 @@ 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)
-- 
2.7.4