RE: [PATCH] eal/linux: unregister alarm callback before free ptr

[Konstantin Ananyev <konstantin.ananyev@huawei.com>]

> Subject: [PATCH] eal/linux: unregister alarm callback before free ptr
> 
> This was flagged by Address sanitizer as a use after free. The
> intr_handle ptr is shared between the main thread and the interrupt
> thread, and the interrupt thread can dereference the ptr after free
> is called when the main thread cleans up (from the alarm callback).
> 
> The interrupt thread never terminates (eal_intr_thread_main) so
> use rte_intr_callback_unregister_sync during cleanup to
> ensure the callback is removed before freeing the ptr.
> 
> To be more defensive clear out the pointer and registration
> variable if we can unregister.
> 
> Bugzilla ID: 1683
> 
> Signed-off-by: Rui Ferreira <rui.ferreira1@h-partners.com>
> ---
>  .mailmap                  | 1 +
>  lib/eal/linux/eal_alarm.c | 9 ++++++++-
>  2 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/.mailmap b/.mailmap
> index d8439b79ce..907c5ea967 100644
> --- a/.mailmap
> +++ b/.mailmap
> @@ -1332,6 +1332,7 @@ Rosen Xu <rosen.xu@altera.com> <rosen.xu@intel.com>
>  Roy Franz <roy.franz@cavium.com>
>  Roy Pledge <roy.pledge@nxp.com>
>  Roy Shterman <roy.shterman@vastdata.com>
> +Rui Ferreira <rui.ferreira1@h-partners.com>
>  Ruifeng Wang <ruifeng.wang@arm.com>
>  Rushil Gupta <rushilg@google.com>
>  Ryan E Hall <ryan.e.hall@intel.com>
> diff --git a/lib/eal/linux/eal_alarm.c b/lib/eal/linux/eal_alarm.c
> index b216a007a3..eb6a21d4f0 100644
> --- a/lib/eal/linux/eal_alarm.c
> +++ b/lib/eal/linux/eal_alarm.c
> @@ -57,7 +57,14 @@ static void eal_alarm_callback(void *arg);
>  void
>  rte_eal_alarm_cleanup(void)
>  {
> -	rte_intr_instance_free(intr_handle);
> +	/* unregister callback using intr_handle in interrupt thread */
> +	int ret = rte_intr_callback_unregister_sync(intr_handle,
> +						eal_alarm_callback, (void *)-1);
> +	if (ret >= 0) {
> +		rte_intr_instance_free(intr_handle);
> +		intr_handle = NULL;
> +		handler_registered = 0;
> +	}
>  }
> 
>  int
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>

As a nit: as it is a bug-fix, probably start with 'fix ..' in the subject.
Also "Fixes:" and probably " Cc: stable@dpdk.org" needs to be added.

> 2.35.3