Re: UBSAN: invalid-load in net/mac80211/status.c:1164:21

From: Johannes Berg <johannes@sipsolutions.net>
To: Bagas Sanjaya <bagasdotme@gmail.com>,
	'Linux Kernel' <linux-kernel@vger.kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	"Kurt Cancemi" <kurt@x64architecture.com>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Toke Høiland-Jørgensen" <toke@redhat.com>
Subject: Re: UBSAN: invalid-load in net/mac80211/status.c:1164:21
Date: Wed, 30 Mar 2022 15:23:06 +0200	[thread overview]
Message-ID: <892635fbacdc171baba2cba1b501f30b6a4faeca.camel@sipsolutions.net> (raw)
In-Reply-To: <395d9e22-8b28-087a-5c5d-61a43db527ac@gmail.com>

On Wed, 2022-03-30 at 18:49 +0700, Bagas Sanjaya wrote:
> 
> [ 1152.928312] UBSAN: invalid-load in net/mac80211/status.c:1164:21
> [ 1152.928318] load of value 255 is not a valid value for type '_Bool'

That's loading status->is_valid_ack_signal, it seems.

Note how that's in a union, shadowed by the 0x00ff0000'00000000 byte of
the control.vif pointer (if I'm counting bytes correctly). That's kind
of expected to be 0xff.

> [ 1152.928323] CPU: 1 PID: 857 Comm: rs:main Q:Reg Not tainted 5.17.1-kernelorg-stable-generic #1
> [ 1152.928329] Hardware name: Acer Aspire E5-571/EA50_HB   , BIOS V1.04 05/06/2014
> [ 1152.928331] Call Trace:
> [ 1152.928334]  <TASK>
> [ 1152.928338]  dump_stack_lvl+0x4c/0x63
> [ 1152.928350]  dump_stack+0x10/0x12
> [ 1152.928354]  ubsan_epilogue+0x9/0x45
> [ 1152.928359]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
> [ 1152.928365]  ieee80211_tx_status_ext.cold+0xa3/0xb8 [mac80211]
> [ 1152.928467]  ieee80211_tx_status+0x7d/0xa0 [mac80211]
> [ 1152.928535]  ath_txq_unlock_complete+0x15c/0x170 [ath9k]
> [ 1152.928553]  ath_tx_edma_tasklet+0xe5/0x4c0 [ath9k]
> [ 1152.928567]  ath9k_tasklet+0x14e/0x280 [ath9k]

Which sort of means that ath9k isn't setting up the status area
correctly?

> The bisection process, starting from v5.17 (the first tag with the warning),
> found first 'oops' commit at 837d9e49402eaf (net: phy: marvell: Fix invalid
> comparison in the resume and suspend functions, 2022-03-12). However, since
> the commit didn't touch net/mac80211/status.c, it wasn't the root cause
> commit.

Well you'd look for something in ath9k, I guess. But you didn't limit
the bisect, so not sure why it went off into the weeds. Maybe you got
one of them wrong.

> The latest commit that touch the file in question is commit
> ea5907db2a9ccf (mac80211: fix struct ieee80211_tx_info size, 2022-02-02).

That's after 5.17 though, and it replaced the bool by just a flag.

Seems to me ath9k should use something like
ieee80211_tx_info_clear_status() or do the memset by itself? This bug
would now not be reported, but it might report the flag erroneously.

johannes