Re: [PATCH stable 5.10 5.15 v2] serial: sc16is7xx: convert from _raw_ to _noinc_ regmap functions for FIFO

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sat, Mar 30, 2024 at 09:25:20AM +0800, GONG, Ruiqi wrote:
> From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> 
> commit dbf4ab821804df071c8b566d9813083125e6d97b upstream.
> 
> The SC16IS7XX IC supports a burst mode to access the FIFOs where the
> initial register address is sent ($00), followed by all the FIFO data
> without having to resend the register address each time. In this mode, the
> IC doesn't increment the register address for each R/W byte.
> 
> The regmap_raw_read() and regmap_raw_write() are functions which can
> perform IO over multiple registers. They are currently used to read/write
> from/to the FIFO, and although they operate correctly in this burst mode on
> the SPI bus, they would corrupt the regmap cache if it was not disabled
> manually. The reason is that when the R/W size is more than 1 byte, these
> functions assume that the register address is incremented and handle the
> cache accordingly.
> 
> Convert FIFO R/W functions to use the regmap _noinc_ versions in order to
> remove the manual cache control which was a workaround when using the
> _raw_ versions. FIFO registers are properly declared as volatile so
> cache will not be used/updated for FIFO accesses.
> 
> Fixes: dfeae619d781 ("serial: sc16is7xx")
> Cc:  <stable@vger.kernel.org> # 5.10 5.15
> Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> Link: https://lore.kernel.org/r/20231211171353.2901416-6-hugo@hugovil.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Hugo Villeneuve <hvilleneuve@dimonoff.com>
> Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
> ---
> 
> v2: Backport to both 5.15 and 5.10
> 
> The mainline commit dbf4ab821804 ("serial: sc16is7xx: convert from _raw_
> to _noinc_ regmap functions for FIFO") by Hugo has been assigned to be
> CVE-2023-52488, but for stable branches lower than 6.1 there's no
> official backport.
> 
> I made up this backport patch for 5.10, and its correctness has been
> confirmed in previous communication with Hugo. Let's publicize it and
> merge it into upstream.

Now queued up, thanks.

greg k-h