Daniel Stone <daniels@xxxxxxxxxxxxx> writes:
> 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@xxxxxxxxxxxxx>
> Cc: Arend Van Spriel <arend.vanspriel@xxxxxxxxxxxx>
> Cc: James Hughes <james.hughes@xxxxxxxxxxxxxxx>
> Cc: Hante Meuleman <hante.meuleman@xxxxxxxxxxxx>
> Cc: Pieter-Paul Giesberts <pieter-paul.giesberts@xxxxxxxxxxxx>
> Cc: Franky Lin <franky.lin@xxxxxxxxxxxx>
I'll queue this for 4.13.
--
Kalle Valo
