Messages in this thread | | | Date | Mon, 29 Aug 2022 12:11:27 +0200 | Subject | Re: 6.0 tty regression, NULL pointer deref in flush_to_ldisc | From | Hans de Goede <> |
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Hi,
On 8/29/22 11:36, Ilpo Järvinen wrote: > On Mon, 29 Aug 2022, Hans de Goede wrote: > >> Hi All, >> >> This weekend I noticed that on various Bay Trail based systems which have >> their bluetooth HCI connected over an uart (using hci_uart driver / >> using the drivers/tty/serial bus) there is a NULL pointer deref in >> flush_to_ldisc, see below for the full backtrace. >> >> I *suspect* that this is caused by commit 6bb6fa6908eb >> ("tty: Implement lookahead to process XON/XOFF timely"). >> >> I can cleanly revert this by reverting the following commits: >> >> ab24a01b2765 ("tty: Add closing marker into comment in tty_ldisc.h") >> 65534736d9a5 ("tty: Use flow-control char function on closing path") >> 6bb6fa6908eb ("tty: Implement lookahead to process XON/XOFF timely") >> >> ATM I don't have one of the affected systems handy. I will give >> a 6.0-rc3 kernel with these 3 commits reverted a try tonight (CEST) >> and I'll let you know the results. >> >> Note I can NOT confirm yet that these reverts fix things, so please >> don't revert anything yet. I just wanted to give people a headsup >> about this issue. >> >> Also maybe we can fix the new lookahead code instead of reverting. >> I would be happy to add a patch adding some debugging prints the >> systems run fine after the backtrace as long as I don't suspend them >> so gathering logs is easy. > > I guess this will help: > > https://lore.kernel.org/linux-kernel/20220818115026.2237893-1-vincent.whitchurch@axis.com/
Ah, yes that indeed looks like it should help. I'll give that a try tonight and report back the result.
Regards,
Hans
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