[Crash-utility] [PATCH] extension/gcore: Fix the invalid struct size failure of pid_link on 4.19 and newer kernel.

[d.hatayama at fujitsu.com]

Masa,

> -----Original Message-----
> From: Masayoshi Mizuma [mailto:msys.mizuma at gmail.com]
> Sent: Monday, June 24, 2019 9:10 AM
...<snip>...
> From: Masayoshi Mizuma <m.mizuma at jp.fujitsu.com>
> 
> On 4.19 and newer kernel, gcore command fails as following:
> 
> ===========================================================
>     gcore: invalid structure size: pid_link
>            FILE: libgcore/gcore_coredump_table.c  LINE: 423  FUNCTION:
> pid_alive()
> 
>     [./crash] error trace: 7f4a7a6762b8 => 7f4a7a676e0f => 53b391 => 53b316
> 
>       53b316: SIZE_verify.part.31+70
>       53b391: SIZE_verify+49
> 
>     gcore: invalid structure size: pid_link
>            FILE: libgcore/gcore_coredump_table.c  LINE: 423  FUNCTION:
> pid_alive()
> 
>     Failed.
> ===========================================================
> 
> That is because struct pid_link is removed and struct pid array is added to
> struct signal_struct by commit 2c4704756cab ("pids: Move the pgrp and session
> pid pointers from task_struct to signal_struct").
> 
> Get the pointer of struct pid from task_struct->thread_pid or
> signal_struct->pids[] to fix the failure.
> 
> Signed-off-by: Masayoshi Mizuma <m.mizuma at jp.fujitsu.com>

The patch looks good to me, and passed my local test set.
I'll include this in the next release.

Thanks.
HATAYAMA, Daisuke

> ---
>  gcore.c                         |  4 +++
>  libgcore/gcore_coredump_table.c | 48 +++++++++++++++++++++++++++------
>  libgcore/gcore_defs.h           |  2 ++
>  3 files changed, 46 insertions(+), 8 deletions(-)
> 
> diff --git a/gcore.c b/gcore.c
> index 65dd7a4..4e1304f 100644
> --- a/gcore.c
> +++ b/gcore.c
> @@ -501,6 +501,10 @@ static void gcore_offset_table_init(void)
>  	GCORE_MEMBER_OFFSET_INIT(vfp_hard_struct_fpscr, "vfp_hard_struct",
> "fpscr");
>  	GCORE_MEMBER_OFFSET_INIT(thread_struct_fpsimd_state,
> "thread_struct", "fpsimd_state");
>  	GCORE_MEMBER_OFFSET_INIT(thread_struct_tp_value, "thread_struct",
> "tp_value");
> +	if (MEMBER_EXISTS("task_struct", "thread_pid"))
> +		GCORE_MEMBER_OFFSET_INIT(task_struct_thread_pid,
> "task_struct", "thread_pid");
> +	if (MEMBER_EXISTS("signal_struct", "pids"))
> +		GCORE_MEMBER_OFFSET_INIT(signal_struct_pids,
> "signal_struct", "pids");
>  }
> 
>  static void gcore_size_table_init(void)
> diff --git a/libgcore/gcore_coredump_table.c
> b/libgcore/gcore_coredump_table.c
> index a073591..4cf9c38 100644
> --- a/libgcore/gcore_coredump_table.c
> +++ b/libgcore/gcore_coredump_table.c
> @@ -224,7 +224,7 @@ __task_pid_nr_ns(ulong task, enum pid_type type)
>  		sizeof(ns), "__task_pid_nr_ns: ns",
> gcore_verbose_error_handle());
> 
>  	if (pid_alive(task)) {
> -		ulong pids_type_pid;
> +		ulong pids_type_pid, signal;
> 
>                  if (type != PIDTYPE_PID)
>  			readmem(task + MEMBER_OFFSET("task_struct",
> @@ -233,10 +233,34 @@ __task_pid_nr_ns(ulong task, enum pid_type type)
>  				"__task_pid_nr_ns: group_leader",
>  				gcore_verbose_error_handle());
> 
> -		readmem(task + OFFSET(task_struct_pids) + type *
> SIZE(pid_link)
> -			+ OFFSET(pid_link_pid), KVADDR, &pids_type_pid,
> -			sizeof(pids_type_pid),
> -			"__task_pid_nr_ns: pids_type_pid",
> gcore_verbose_error_handle());
> +		if (VALID_MEMBER(task_struct_pids))
> +			readmem(task + OFFSET(task_struct_pids) +
> +				type * SIZE(pid_link) +
> OFFSET(pid_link_pid),
> +				KVADDR, &pids_type_pid,
> +				sizeof(pids_type_pid),
> +				"__task_pid_nr_ns: pids_type_pid",
> +				gcore_verbose_error_handle());
> +		else
> +			if (type == PIDTYPE_PID)
> +				readmem(task +
> GCORE_OFFSET(task_struct_thread_pid),
> +					KVADDR, &pids_type_pid,
> +					sizeof(pids_type_pid),
> +					"__task_pid_nr_ns:
> pids_type_pid",
> +					gcore_verbose_error_handle());
> +			else {
> +				readmem(task +
> OFFSET(task_struct_signal),
> +					KVADDR, &signal,
> +					sizeof(signal),
> +					"__task_pid_nr_ns: signal",
> +					gcore_verbose_error_handle());
> +
> +				readmem(signal +
> GCORE_OFFSET(signal_struct_pids) +
> +					type * sizeof(void *),
> +					KVADDR, &pids_type_pid,
> +					sizeof(pids_type_pid),
> +					"__task_pid_nr_ns:
> pids_type_pid",
> +					gcore_verbose_error_handle());
> +			}
> 
>  		nr = pid_nr_ns(pids_type_pid, ns);
>          }
> @@ -420,9 +444,17 @@ pid_alive(ulong task)
>  {
>  	pid_t pid;
> 
> -	readmem(task + OFFSET(task_struct_pids) + PIDTYPE_PID *
> SIZE(pid_link)
> -		+ OFFSET(pid_link_pid), KVADDR, &pid, sizeof(pid),
> "pid_alive",
> -		gcore_verbose_error_handle());
> +	if (VALID_MEMBER(task_struct_pids))
> +		readmem(task + OFFSET(task_struct_pids) +
> +			PIDTYPE_PID * SIZE(pid_link) +
> OFFSET(pid_link_pid),
> +			KVADDR, &pid, sizeof(pid),
> +			"pid_alive",
> +			gcore_verbose_error_handle());
> +	else
> +		readmem(task + GCORE_OFFSET(task_struct_thread_pid),
> +			KVADDR, &pid, sizeof(pid),
> +			"task_struct.thread_pid",
> +			gcore_verbose_error_handle());
> 
>          return !!pid;
>  }
> diff --git a/libgcore/gcore_defs.h b/libgcore/gcore_defs.h
> index 18c4c2c..3c839f9 100644
> --- a/libgcore/gcore_defs.h
> +++ b/libgcore/gcore_defs.h
> @@ -1077,6 +1077,7 @@ struct gcore_offset_table
>  	long sched_entity_sum_exec_runtime;
>  	long signal_struct_cutime;
>  	long signal_struct_pgrp;
> +	long signal_struct_pids;
>  	long signal_struct_session;
>  	long signal_struct_stime;
>  	long signal_struct_sum_sched_runtime;
> @@ -1090,6 +1091,7 @@ struct gcore_offset_table
>  	long task_struct_static_prio;
>  	long task_struct_uid;
>  	long task_struct_used_math;
> +	long task_struct_thread_pid;
>  	long thread_info_status;
>  	long thread_info_fpstate;
>  	long thread_info_vfpstate;
> --
> 2.18.1