This is a note to let you know that I've just added the patch titled
wifi: cfg80211: fix UBSAN noise in cfg80211_wext_siwscan()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
wifi-cfg80211-fix-ubsan-noise-in-cfg80211_wext_siwsc.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 06cfc01ead4719856e01190f038315d39ea5d6b9
Author: Dmitry Antipov <dmantipov@xxxxxxxxx>
Date: Thu Sep 5 18:04:00 2024 +0300
wifi: cfg80211: fix UBSAN noise in cfg80211_wext_siwscan()
[ Upstream commit a26a5107bc52922cf5f67361e307ad66547b51c7 ]
Looking at https://syzkaller.appspot.com/bug?extid=1a3986bbd3169c307819
and running reproducer with CONFIG_UBSAN_BOUNDS, I've noticed the
following:
[ T4985] UBSAN: array-index-out-of-bounds in net/wireless/scan.c:3479:25
[ T4985] index 164 is out of range for type 'struct ieee80211_channel *[]'
<...skipped...>
[ T4985] Call Trace:
[ T4985] <TASK>
[ T4985] dump_stack_lvl+0x1c2/0x2a0
[ T4985] ? __pfx_dump_stack_lvl+0x10/0x10
[ T4985] ? __pfx__printk+0x10/0x10
[ T4985] __ubsan_handle_out_of_bounds+0x127/0x150
[ T4985] cfg80211_wext_siwscan+0x11a4/0x1260
<...the rest is not too useful...>
Even if we do 'creq->n_channels = n_channels' before 'creq->ssids =
(void *)&creq->channels[n_channels]', UBSAN treats the latter as
off-by-one error. Fix this by using pointer arithmetic rather than
an expression with explicit array indexing and use convenient
'struct_size()' to simplify the math here and in 'kzalloc()' above.
Fixes: 5ba63533bbf6 ("cfg80211: fix alignment problem in scan request")
Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx>
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
Link: https://patch.msgid.link/20240905150400.126386-1-dmantipov@xxxxxxxxx
[fix coding style for multi-line calculation]
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index b8e28025710dd..dc41b31073e75 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2813,8 +2813,8 @@ int cfg80211_wext_siwscan(struct net_device *dev,
n_channels = ieee80211_get_num_supported_channels(wiphy);
}
- creq = kzalloc(sizeof(*creq) + sizeof(struct cfg80211_ssid) +
- n_channels * sizeof(void *),
+ creq = kzalloc(struct_size(creq, channels, n_channels) +
+ sizeof(struct cfg80211_ssid),
GFP_ATOMIC);
if (!creq) {
err = -ENOMEM;
@@ -2824,7 +2824,7 @@ int cfg80211_wext_siwscan(struct net_device *dev,
creq->wiphy = wiphy;
creq->wdev = dev->ieee80211_ptr;
/* SSIDs come after channels */
- creq->ssids = (void *)&creq->channels[n_channels];
+ creq->ssids = (void *)creq + struct_size(creq, channels, n_channels);
creq->n_channels = n_channels;
creq->n_ssids = 1;
creq->scan_start = jiffies;
