diff mbox

brcmfmac: Don't grow SKB by negative size

Message ID 20170726083742.5420-1-daniels@collabora.com (mailing list archive)
State Superseded
Delegated to: Kalle Valo
Headers show

Commit Message

Daniel Stone July 26, 2017, 8:37 a.m. UTC
The commit to rework the headroom check in start_xmit() now calls
pxskb_expand_head() unconditionally if the header is CoW. Unfortunately,
it does so with the delta between the extant headroom and the header
length, which may be negative if there is already sufficient headroom.

pskb_expand_head() does allow for size being 0, in which case it just
copies, so clamp the header delta to zero.

Opening Chrome (and all my tabs) on a PCIE device was enough to reliably
hit this.

Fixes: 270a6c1f65fe ("brcmfmac: rework headroom check in .start_xmit()")
Signed-off-by: Daniel Stone <daniels@collabora.com>
Cc: Arend Van Spriel <arend.vanspriel@broadcom.com>
Cc: James Hughes <james.hughes@raspberrypi.org>
Cc: Hante Meuleman <hante.meuleman@broadcom.com>
Cc: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Cc: Franky Lin <franky.lin@broadcom.com>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Hi,
It would be great to get this in to 4.13. Otherwise, just opening
Chrome is enough to take my machine down in ~5 seconds.

Cheers,
Daniel
diff mbox

Patch

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
index 2153e8062b4c..ee91a411918c 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
@@ -214,7 +214,7 @@  static netdev_tx_t brcmf_netdev_start_xmit(struct sk_buff *skb,
 
 	/* Make sure there's enough writeable headroom */
 	if (skb_headroom(skb) < drvr->hdrlen || skb_header_cloned(skb)) {
-		head_delta = drvr->hdrlen - skb_headroom(skb);
+		head_delta = min(drvr->hdrlen - skb_headroom(skb), 0);
 
 		brcmf_dbg(INFO, "%s: insufficient headroom (%d)\n",
 			  brcmf_ifname(ifp), head_delta);