Fork of alistair23 Linux kernel for reMarkable from https://github.com/alistair23/linux
21a8e9dd52
Existing API 'ieee80211_get_sdata_band' returns default 2 GHz band even if the channel context configuration is NULL. This crashes for chipsets which support 5 Ghz alone when it tries to access members of 'sband'. Channel context configuration can be NULL in multivif case and when channel switch is in progress (or) when it fails. Fix this by replacing the API 'ieee80211_get_sdata_band' with 'ieee80211_get_sband' which returns a NULL pointer for sband when the channel configuration is NULL. An example scenario is as below: In multivif mode (AP + STA) with drivers like ath10k, when we do a channel switch in the AP vif (which has a number of clients connected) and a STA vif which is connected to some other AP, when the channel switch in AP vif fails, while the STA vifs tries to connect to the other AP, there is a window where the channel context is NULL/invalid and this results in a crash while the clients connected to the AP vif tries to reconnect and this race is very similar to the one investigated by Michal in https://patchwork.kernel.org/patch/3788161/ and this does happens with hardware that supports 5Ghz alone after long hours of testing with continuous channel switch on the AP vif ieee80211 phy0: channel context reservation cannot be finalized because some interfaces aren't switching wlan0: failed to finalize CSA, disconnecting wlan0-1: deauthenticating from 8c:fd:f0:01:54:9c by local choice (Reason: 3=DEAUTH_LEAVING) WARNING: CPU: 1 PID: 19032 at net/mac80211/ieee80211_i.h:1013 sta_info_alloc+0x374/0x3fc [mac80211] [<bf77272c>] (sta_info_alloc [mac80211]) [<bf78776c>] (ieee80211_add_station [mac80211])) [<bf73cc50>] (nl80211_new_station [cfg80211]) Unable to handle kernel NULL pointer dereference at virtual address 00000014 pgd = d5f4c000 Internal error: Oops: 17 [#1] PREEMPT SMP ARM PC is at sta_info_alloc+0x380/0x3fc [mac80211] LR is at sta_info_alloc+0x37c/0x3fc [mac80211] [<bf772738>] (sta_info_alloc [mac80211]) [<bf78776c>] (ieee80211_add_station [mac80211]) [<bf73cc50>] (nl80211_new_station [cfg80211])) Cc: Michal Kazior <michal.kazior@tieto.com> Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.