linux-kernel - Re: [PATCH v3 06/11] i3c: master: svc: use repeat start when IBI WIN happens

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240823180930.5fa341d3@xps-13>
Date: Fri, 23 Aug 2024 18:09:30 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Frank Li <Frank.Li@....com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>, Boris Brezillon
 <boris.brezillon@...labora.com>, Parshuram Thombare <pthombar@...ence.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Boris Brezillon
 <bbrezillon@...nel.org>, Arnd Bergmann <arnd@...db.de>, Conor Culhane
 <conor.culhane@...vaco.com>, linux-i3c@...ts.infradead.org,
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev
Subject: Re: [PATCH v3 06/11] i3c: master: svc: use repeat start when IBI
 WIN happens

Hi Frank,

Frank.Li@....com wrote on Mon, 19 Aug 2024 12:02:00 -0400:

> There is a possibility of an IBI WIN occurring when addressing issues, even
> when sending CCC commands. Most of the time, returning -EAGAIN is
> acceptable, but the case below becomes highly complex.
> 
> When a Hotjoin event occurs:
> - i3c_master_do_daa()
>   - i3c_master_add_i3c_dev_locked()
>     - A dynamic address (e.g., 0x9) is already set during DAA.
>     - i3c_master_getpid_locked()
>       - Another device issues HJ or IBI here. Returning -EAGAIN causes
>         failure in adding the new device. However, the dynamic address(0x9)
>         has already been assigned to this device. If another device issues
>         HJ, it will get this address 0x9 again, causing two devices on the
>         bus to use the same dynamic address 0x9.
>       - Attempting to send RSTDAA when the first device fails at
>         i3c_master_getpid_locked() could also fail when sending RSTDAA for
>         the same reason.
> 
> According to the I3C spec, address arbitration only happens at START, never
> at REPEAT start. Using repeat start when an IBI WIN occurs simplifies this
> case, as i3c_master_getpid_locked() will not return an error when another
> device tries to send HJ or IBI.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>

Feels sensible.

Acked-by: Miquel Raynal <miquel.raynal@...tlin.com>

Thanks,
Miquèl