| Message ID | 20211118203839.1289276-1-keescook@chromium.org (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | mac80211: Use memset_after() to clear tx status | expand |
On 18/11/2021 21:38, Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_after() so memset() doesn't get confused about writing > beyond the destination member that is intended to be the starting point > of zeroing through the end of the struct. > > Additionally fix the common helper, ieee80211_tx_info_clear_status(), > which was not clearing ack_signal, but the open-coded versions > did. Johannes Berg points out this bug was introduced by commit > e3e1a0bcb3f1 ("mac80211: reduce IEEE80211_TX_MAX_RATES") but was harmless. > > Also drops the associated unneeded BUILD_BUG_ON()s, and adds a note to > carl9170 about usage. > > Signed-off-by: Kees Cook <keescook@chromium.org> Tested-by: Christian Lamparter <chunkeey@gmail.com> [both CARL9170+P54USB on real HW]
On Sat, 2021-11-20 at 16:17 +0100, Christian Lamparter wrote: > > Tested-by: Christian Lamparter <chunkeey@gmail.com> [both CARL9170+P54USB on real HW] > Thanks! johannes
diff --git a/drivers/net/wireless/ath/carl9170/tx.c b/drivers/net/wireless/ath/carl9170/tx.c index 88444fe6d1c6..1b76f4434c06 100644 --- a/drivers/net/wireless/ath/carl9170/tx.c +++ b/drivers/net/wireless/ath/carl9170/tx.c @@ -275,12 +275,12 @@ static void carl9170_tx_release(struct kref *ref) if (WARN_ON_ONCE(!ar)) return; - BUILD_BUG_ON( - offsetof(struct ieee80211_tx_info, status.ack_signal) != 20); - - memset(&txinfo->status.ack_signal, 0, - sizeof(struct ieee80211_tx_info) - - offsetof(struct ieee80211_tx_info, status.ack_signal)); + /* + * This does not call ieee80211_tx_info_clear_status() because + * carl9170_tx_fill_rateinfo() has filled the rate information + * before we get to this point. + */ + memset_after(&txinfo->status, 0, rates); if (atomic_read(&ar->tx_total_queued)) ar->tx_schedule = true; diff --git a/drivers/net/wireless/intersil/p54/txrx.c b/drivers/net/wireless/intersil/p54/txrx.c index 873fea59894f..8414aa208655 100644 --- a/drivers/net/wireless/intersil/p54/txrx.c +++ b/drivers/net/wireless/intersil/p54/txrx.c @@ -431,11 +431,7 @@ static void p54_rx_frame_sent(struct p54_common *priv, struct sk_buff *skb) * Clear manually, ieee80211_tx_info_clear_status would * clear the counts too and we need them. */ - memset(&info->status.ack_signal, 0, - sizeof(struct ieee80211_tx_info) - - offsetof(struct ieee80211_tx_info, status.ack_signal)); - BUILD_BUG_ON(offsetof(struct ieee80211_tx_info, - status.ack_signal) != 20); + memset_after(&info->status, 0, rates); if (entry_hdr->flags & cpu_to_le16(P54_HDR_FLAG_DATA_ALIGN)) pad = entry_data->align[0]; diff --git a/include/net/mac80211.h b/include/net/mac80211.h index dd757f0987b0..a648484bde33 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -1205,12 +1205,7 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info) /* clear the rate counts */ for (i = 0; i < IEEE80211_TX_MAX_RATES; i++) info->status.rates[i].count = 0; - - BUILD_BUG_ON( - offsetof(struct ieee80211_tx_info, status.ack_signal) != 20); - memset(&info->status.ampdu_ack_len, 0, - sizeof(struct ieee80211_tx_info) - - offsetof(struct ieee80211_tx_info, status.ampdu_ack_len)); + memset_after(&info->status, 0, rates); }
In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memset(), avoid intentionally writing across neighboring fields. Use memset_after() so memset() doesn't get confused about writing beyond the destination member that is intended to be the starting point of zeroing through the end of the struct. Additionally fix the common helper, ieee80211_tx_info_clear_status(), which was not clearing ack_signal, but the open-coded versions did. Johannes Berg points out this bug was introduced by commit e3e1a0bcb3f1 ("mac80211: reduce IEEE80211_TX_MAX_RATES") but was harmless. Also drops the associated unneeded BUILD_BUG_ON()s, and adds a note to carl9170 about usage. Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/net/wireless/ath/carl9170/tx.c | 12 ++++++------ drivers/net/wireless/intersil/p54/txrx.c | 6 +----- include/net/mac80211.h | 7 +------ 3 files changed, 8 insertions(+), 17 deletions(-)