brcmfmac: p2p: Replace one-element arrays with flexible-array members

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

This issue was found with the help of Coccinelle and audited and fixed,
manually.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220204232228.GA442895@embeddedor

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
index 4735063..d3f08d4 100644 (file)
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c
@@ -158,7 +158,7 @@ struct brcmf_p2p_pub_act_frame {
        u8      oui_type;
        u8      subtype;
        u8      dialog_token;
-       u8      elts[1];
+       u8      elts[];
 };
 
 /**
@@ -177,7 +177,7 @@ struct brcmf_p2p_action_frame {
        u8      type;
        u8      subtype;
        u8      dialog_token;
-       u8      elts[1];
+       u8      elts[];
 };
 
 /**
@@ -192,7 +192,7 @@ struct brcmf_p2psd_gas_pub_act_frame {
        u8      category;
        u8      action;
        u8      dialog_token;
-       u8      query_data[1];
+       u8      query_data[];
 };
 
 /**
@@ -225,7 +225,7 @@ static bool brcmf_p2p_is_pub_action(void *frame, u32 frame_len)
                return false;
 
        pact_frm = (struct brcmf_p2p_pub_act_frame *)frame;
-       if (frame_len < sizeof(struct brcmf_p2p_pub_act_frame) - 1)
+       if (frame_len < sizeof(*pact_frm))
                return false;
 
        if (pact_frm->category == P2P_PUB_AF_CATEGORY &&
@@ -253,7 +253,7 @@ static bool brcmf_p2p_is_p2p_action(void *frame, u32 frame_len)
                return false;
 
        act_frm = (struct brcmf_p2p_action_frame *)frame;
-       if (frame_len < sizeof(struct brcmf_p2p_action_frame) - 1)
+       if (frame_len < sizeof(*act_frm))
                return false;
 
        if (act_frm->category == P2P_AF_CATEGORY &&
@@ -280,7 +280,7 @@ static bool brcmf_p2p_is_gas_action(void *frame, u32 frame_len)
                return false;
 
        sd_act_frm = (struct brcmf_p2psd_gas_pub_act_frame *)frame;
-       if (frame_len < sizeof(struct brcmf_p2psd_gas_pub_act_frame) - 1)
+       if (frame_len < sizeof(*sd_act_frm))
                return false;
 
        if (sd_act_frm->category != P2PSD_ACTION_CATEGORY)