[Crash-utility] [PATCH] Fix for an abort in vm_stat_init() without CONFIG_NUMA

[Dave Anderson]

----- Original Message -----
> With recent kernels without CONFIG_NUMA (including Fedora 32-bit),
> the vm_stat_init() function aborts when getting numa_stat_item
> enum items, (probably) because it is not defined.
> 
>   crash> kmem -V
>   double free or corruption (!prev)
>   Aborted (core dumped)
> 
> We can avoid the abort by checking whether the length of the
> vm_numa_stat array is also not zero.
> 
> This patch tested OK with the following kernels:
>   4.17.0-0.rc5.git3.1.fc29.i686
>   4.18.0-0.rc5.git4.1.fc29.x86_64
>   3.10.0-862.el7.x86_64
> 
> Signed-off-by: Kazuhito Hagio <k-hagio at ab.jp.nec.com>

Thanks Kazu, looks good.  Queued for crash-7.2.4:
  
  https://github.com/crash-utility/crash/commit/d2a164e5f1b774f2b8aec137a2ad9c7eb905b650

Dave


> ---
>  defs.h    |  1 +
>  memory.c  | 10 ++++++----
>  symbols.c |  4 ++++
>  3 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/defs.h b/defs.h
> index f569a62..6fdb478 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2220,6 +2220,7 @@ struct array_table {
>  	int height_to_maxnodes;
>  	int task_struct_rlim;
>  	int signal_struct_rlim;
> +	int vm_numa_stat;
>  };
>  
>  /*
> diff --git a/memory.c b/memory.c
> index 7c0cb5f..e02ba68 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -17454,11 +17454,12 @@ vm_stat_init(void)
>  		} else if (symbol_exists("vm_zone_stat") &&
>  			get_symbol_type("vm_zone_stat",
>  			NULL, NULL) == TYPE_CODE_ARRAY) {
> -			if (symbol_exists("vm_numa_stat")) {
> +			if (symbol_exists("vm_numa_stat") &&
> +			    get_array_length("vm_numa_stat", NULL, 0)) {
>  				vt->nr_vm_stat_items =
>  					get_array_length("vm_zone_stat", NULL, 0)
>  					+ get_array_length("vm_node_stat", NULL, 0)
> -					+ get_array_length("vm_numa_stat", NULL, 0);
> +					+ ARRAY_LENGTH(vm_numa_stat);
>  				split_vmstat = 2;
>  				enumerator_value("NR_VM_ZONE_STAT_ITEMS", &zone_cnt);
>  				enumerator_value("NR_VM_NODE_STAT_ITEMS", &node_cnt);
> @@ -17599,7 +17600,7 @@ dump_vm_stat(char *item, long *retval, ulong zone)
>  	buf = GETBUF(sizeof(ulong) * vt->nr_vm_stat_items);
>  
>  	if (symbol_exists("vm_node_stat") && symbol_exists("vm_zone_stat") &&
> -	    symbol_exists("vm_numa_stat"))
> +	    symbol_exists("vm_numa_stat") && ARRAY_LENGTH(vm_numa_stat))
>  		split_vmstat = 2;
>  	else if (symbol_exists("vm_node_stat") && symbol_exists("vm_zone_stat"))
>  		split_vmstat = 1;
> @@ -17666,7 +17667,8 @@ dump_vm_stat(char *item, long *retval, ulong zone)
>  			if (!zone) {
>  				if ((i == node_start) && symbol_exists("vm_node_stat"))
>  					fprintf(fp, "\n  VM_NODE_STAT:\n");
> -				if ((i == numa_start) && symbol_exists("vm_numa_stat"))
> +				if ((i == numa_start) && symbol_exists("vm_numa_stat")
> +				    && ARRAY_LENGTH(vm_numa_stat))
>  					fprintf(fp, "\n  VM_NUMA_STAT:\n");
>  			}
>  			fprintf(fp, "%s%s: %ld\n",
> diff --git a/symbols.c b/symbols.c
> index df84ee2..bee60ba 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -8457,6 +8457,8 @@ builtin_array_length(char *s, int len, int *two_dim)
>  		lenptr = &array_table.task_struct_rlim;
>  	else if (STREQ(s, "signal_struct.rlim"))
>  		lenptr = &array_table.signal_struct_rlim;
> +	else if (STREQ(s, "vm_numa_stat"))
> +		lenptr = &array_table.vm_numa_stat;
>  
>  	if (!lenptr)                /* not stored */
>  		return(len);
> @@ -10594,6 +10596,8 @@ dump_offset_table(char *spec, ulong makestruct)
>  		ARRAY_LENGTH(task_struct_rlim));
>  	fprintf(fp, "            signal_struct_rlim: %d\n",
>  		ARRAY_LENGTH(signal_struct_rlim));
> +	fprintf(fp, "                  vm_numa_stat: %d\n",
> +		ARRAY_LENGTH(vm_numa_stat));
>  
>  	if (spec) {
>  		int in_size_table, in_array_table, arrays, offsets, sizes;
> --
> 1.8.3.1
> 
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