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libertas_tf: Use struct_group() for memcpy() region

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In preparation for FORTIFY_SOURCE performing compile-time and run-time
field array bounds checking for memcpy(), memmove(), and memset(),
avoid intentionally writing across neighboring fields.

Use struct_group() in struct txpd around members tx_dest_addr_high
and tx_dest_addr_low so they can be referenced together. This will
allow memcpy() and sizeof() to more easily reason about sizes, improve
readability, and avoid future warnings about writing beyond the end
of tx_dest_addr_high.

"pahole" shows no size nor member offset changes to struct txpd.
"objdump -d" shows no object code changes.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211118184121.1283821-1-keescook@chromium.org
This commit is contained in:
Kees Cook 2021-11-18 10:41:21 -08:00 committed by Kalle Valo
parent 5fd32ae043
commit 642a57475b
2 changed files with 8 additions and 5 deletions
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10
drivers/net/wireless/marvell/libertas_tf/libertas_tf.h
View File

@ -268,10 +268,12 @@ struct txpd {
__le32 tx_packet_location;
/* Tx packet length */
__le16 tx_packet_length;
/* First 2 byte of destination MAC address */
u8 tx_dest_addr_high[2];
/* Last 4 byte of destination MAC address */
u8 tx_dest_addr_low[4];
struct_group(tx_dest_addr,
/* First 2 byte of destination MAC address */
u8 tx_dest_addr_high[2];
/* Last 4 byte of destination MAC address */
u8 tx_dest_addr_low[4];
);
/* Pkt Priority */
u8 priority;
/* Pkt Trasnit Power control */

3
drivers/net/wireless/marvell/libertas_tf/main.c
View File

@ -232,7 +232,8 @@ static void lbtf_tx_work(struct work_struct *work)
ieee80211_get_tx_rate(priv->hw, info)->hw_value);
/* copy destination address from 802.11 header */
memcpy(txpd->tx_dest_addr_high, skb->data + sizeof(struct txpd) + 4,
BUILD_BUG_ON(sizeof(txpd->tx_dest_addr) != ETH_ALEN);
memcpy(&txpd->tx_dest_addr, skb->data + sizeof(struct txpd) + 4,
ETH_ALEN);
txpd->tx_packet_length = cpu_to_le16(len);
txpd->tx_packet_location = cpu_to_le32(sizeof(struct txpd));