Re: [PATCH REPOST net v2] atm/fore200e: Fix possible data race in fore200e_open()

[Gui-Dong Han]

On Thu, Nov 20, 2025 at 7:26 PM Paolo Abeni <pabeni@xxxxxxxxxx> wrote:
>
> On 11/18/25 4:33 AM, Gui-Dong Han wrote:
> > Protect access to fore200e->available_cell_rate with rate_mtx lock to
> > prevent potential data race.
> >
> > In this case, since the update depends on a prior read, a data race
> > could lead to a wrong fore200e.available_cell_rate value.
> >
> > The field fore200e.available_cell_rate is generally protected by the lock
> > fore200e.rate_mtx when accessed. In all other read and write cases, this
> > field is consistently protected by the lock, except for this case and
> > during initialization.
> >
> > This potential bug was detected by our experimental static analysis tool,
> > which analyzes locking APIs and paired functions to identify data races
> > and atomicity violations.
> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Gui-Dong Han <hanguidong02@xxxxxxxxx>
> > Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
> > ---
> > v2:
> > * Added a description of the data race hazard in fore200e_open(), as
> > suggested by Jakub Kicinski and Simon Horman.
>
> It looks like you missed Jakub's reply on v2:
>
> https://lore.kernel.org/netdev/20250123071201.3d38d8f6@xxxxxxxxxx/
>
> The above comment is still not sufficient: you should describe
> accurately how 2 (or more) CPUs could actually race causing the
> corruption, reporting the relevant call paths leading to the race.

Hi Paolo,

Added the detailed description in v3.

Thank you,
Gui-Dong Han