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Date: Tue, 18 Apr 2023 23:00:13 +0300
From: 0xef967c36@...il.com
To: Ruihan Li <lrh2000@....edu.cn>
Cc: 0xef967c36@...il.com, oss-security@...ts.openwall.com,
Solar Designer <solar@...nwall.com>
Subject: Re: CVE-2023-2002: Linux Bluetooth: Unauthorized
management command execution
On Wed, Apr 19, 2023 at 02:37:35AM +0800, Ruihan Li wrote:
> It appears that SNDCTL_TMR_TIMEBASE and TCGETS do have the same command code,
> which sits in the lower 16 bits. But SNDCTL_TMR_TIMEBASE uses a newer command
> encoding scheme [2] that includes the direction and argument size in the
> higher 16 bits. TCGETS, on the other hand, contains only the command code, so
That encoding scheme is quite old; it's there since at least 30 years.
> its higher bits are set to zero (TCGETS should have a really long history,
> just longer than that of the new ioctl command encoding scheme).
>
> [2]: https://elixir.bootlin.com/linux/v6.3-rc7/source/include/uapi/asm-generic/ioctl.h#L5
>
> This means we haven't had any collisions yet. Also, since new ioctl commands
There actually are some collisions, just not the one with isatty() -> TCGETS
eg SNDCTL_TMR_START == TCSETS
> will certainly be encoded using the new encoding scheme, which TCGETS does not
> use, it is very unlikely that new collisions will occur in the future, unless
> the command code is exactly the same and the higher bits under the new
> encoding scheme are also occasionally zeros.
The _IO variant (without direction and size) can collide with
old-style ioctl, like those CDROM*, etc.
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