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mac80211: avoid kernel panic when building AMSDU from non-linear SKB

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When building building AMSDU from non-linear SKB, we hit a
kernel panic when trying to push the padding to the tail.
Instead, put the padding at the head of the next subframe.
This also fixes the A-MSDU subframes to not have the padding
accounted in the length field and not have pad at all for
the last subframe, both required by the spec.

Fixes: 6e0456b545 ("mac80211: add A-MSDU tx support")
Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Reviewed-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Sara Sharon 2018-08-29 08:57:02 +02:00 committed by Johannes Berg
parent 1f631c3201
commit 166ac9d55b
1 changed files with 21 additions and 17 deletions
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38
net/mac80211/tx.c
View File

@ -3073,27 +3073,18 @@ void ieee80211_clear_fast_xmit(struct sta_info *sta)
}
static bool ieee80211_amsdu_realloc_pad(struct ieee80211_local *local,
struct sk_buff *skb, int headroom,
int *subframe_len)
struct sk_buff *skb, int headroom)
{
int amsdu_len = *subframe_len + sizeof(struct ethhdr);
int padding = (4 - amsdu_len) & 3;
if (skb_headroom(skb) < headroom || skb_tailroom(skb) < padding) {
if (skb_headroom(skb) < headroom) {
I802_DEBUG_INC(local->tx_expand_skb_head);
if (pskb_expand_head(skb, headroom, padding, GFP_ATOMIC)) {
if (pskb_expand_head(skb, headroom, 0, GFP_ATOMIC)) {
wiphy_debug(local->hw.wiphy,
"failed to reallocate TX buffer\n");
return false;
}
}
if (padding) {
*subframe_len += padding;
skb_put_zero(skb, padding);
}
return true;
}
@ -3117,8 +3108,7 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
if (info->control.flags & IEEE80211_TX_CTRL_AMSDU)
return true;
if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr),
&subframe_len))
if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr)))
return false;
data = skb_push(skb, sizeof(*amsdu_hdr));
@ -3184,7 +3174,8 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
void *data;
bool ret = false;
unsigned int orig_len;
int n = 1, nfrags;
int n = 1, nfrags, pad = 0;
u16 hdrlen;
if (!ieee80211_hw_check(&local->hw, TX_AMSDU))
return false;
@ -3235,8 +3226,19 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
if (max_frags && nfrags > max_frags)
goto out;
if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) + 2,
&subframe_len))
/*
* Pad out the previous subframe to a multiple of 4 by adding the
* padding to the next one, that's being added. Note that head->len
* is the length of the full A-MSDU, but that works since each time
* we add a new subframe we pad out the previous one to a multiple
* of 4 and thus it no longer matters in the next round.
*/
hdrlen = fast_tx->hdr_len - sizeof(rfc1042_header);
if ((head->len - hdrlen) & 3)
pad = 4 - ((head->len - hdrlen) & 3);
if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(rfc1042_header) +
2 + pad))
goto out;
ret = true;
@ -3248,6 +3250,8 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
memcpy(data, &len, 2);
memcpy(data + 2, rfc1042_header, sizeof(rfc1042_header));
memset(skb_push(skb, pad), 0, pad);
head->len += skb->len;
head->data_len += skb->len;
*frag_tail = skb;