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It was observed that the codepath for the ATH11K_SKB_HW_80211_ENCAP was
used even when the IEEE80211_TX_CTRL_HW_80211_ENCAP was not enabled for a
an skbuff. This became even more prominent when the QCAs wlan-open patchset
for ath11k [1] was applied and a sane looking fix just caused crashes when
injecting frames via a monitor interface (for example with ratechecker):
[ 86.963152] Unable to handle kernel NULL pointer dereference at virtual address 00000338
[ 86.963192] pgd = ffffffc0008f0000
[ 86.971034] [00000338] *pgd=0000000051706003, *pud=0000000051706003, *pmd=0000000051707003, *pte=00e800000b000707
[ 86.984292] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[...]
[ 87.713339] [<ffffffbffc802480>] ieee80211_tx_status_8023+0xf8/0x220 [mac80211]
[ 87.715654] [<ffffffbffc98bad4>] ath11k_dp_tx_completion_handler+0x42c/0xa10 [ath11k]
[ 87.722924] [<ffffffbffc989190>] ath11k_dp_service_srng+0x70/0x3c8 [ath11k]
[ 87.730831] [<ffffffbffca03460>] 0xffffffbffca03460
[ 87.737599] [<ffffffc00046ef58>] net_rx_action+0xf8/0x288
[ 87.742462] [<ffffffc000097554>] __do_softirq+0xfc/0x220
[ 87.748014] [<ffffffc000097900>] irq_exit+0x98/0xe8
[ 87.753396] [<ffffffc0000cf188>] __handle_domain_irq+0x90/0xb8
[ 87.757999] [<ffffffc000081ca4>] gic_handle_irq+0x6c/0xc8
[ 87.763899] Exception stack(0xffffffc00081bdc0 to 0xffffffc00081bef0)
Problem is that the state of ath11k_skb_cb->flags must be considered
unknown and could contain anything when it is not manually initialized. So
it could also contain ATH11K_SKB_HW_80211_ENCAP. And this can result in the
code to assume that the ath11k_skb_cb->vif is set - even when this is not
always the case for non ATH11K_SKB_HW_80211_ENCAP transmissions.
Tested-on: IPQ8074 hw2.0 WLAN.HK.2.4.0.1.r1-00026-QCAHKSWPL_SILICONZ-2
[1] https://source.codeaurora.org/quic/qsdk/oss/system/feeds/wlan-open/tree/mac80211/patches?h=NHSS.QSDK.11.4.r3
(162 patches at the moment which are often not upstreamed but essential
to get ath11k working)
Fixes: e7f33e0c52 ("ath11k: add tx hw 802.11 encapsulation offloading support")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201119154235.263250-2-sven@narfation.org
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.