commit 6d0d95ecc04a70f8448d562ff0fbbae237f5c929

 Author: Kazuhito Hagio <k-hagio-ab@nec.com>

 Date:   Thu Apr 21 08:58:29 2022 +0900

     [PATCH] Avoid false-positive mem_section validation with vmlinux

     Currently get_mem_section() validates if SYMBOL(mem_section) is the address

     of the mem_section array first.  But there was a report that the first

     validation wrongly returned TRUE with -x vmlinux and SPARSEMEM_EXTREME

     (4.15+) on s390x.  This leads to crash failing statup with the following

     seek error:

       crash: seek error: kernel virtual address: 67fffc2800  type: "memory section root table"

     Skip the first validation when satisfying the conditions.

     Reported-by: Dave Wysochanski <dwysocha@redhat.com>

     Signed-off-by: Kazuhito Hagio <k-hagio-ab@nec.com>

     Reviewed-and-Tested-by: Philipp Rudo <prudo@redhat.com>

     Reviewed-by: Pingfan Liu <piliu@redhat.com>

 diff --git a/makedumpfile-1.7.1/makedumpfile.c b/makedumpfile-1.7.1/makedumpfile.c

 index a2f45c84cee3ba57ce3d3cf3f1905e6a03f4fd09..65d1c7c2f02c9ae8ead9de0f0217235fe72b3ca7 100644

 --- a/makedumpfile-1.7.1/makedumpfile.c

 +++ b/makedumpfile-1.7.1/makedumpfile.c

 @@ -3698,6 +3698,22 @@ validate_mem_section(unsigned long *mem_sec,

  	return ret;

  }

 +/*

 + * SYMBOL(mem_section) varies with the combination of memory model and

 + * its source:

 + *

 + * SPARSEMEM

 + *   vmcoreinfo: address of mem_section root array

 + *   -x vmlinux: address of mem_section root array

 + *

 + * SPARSEMEM_EXTREME v1

 + *   vmcoreinfo: address of mem_section root array

 + *   -x vmlinux: address of mem_section root array

 + *

 + * SPARSEMEM_EXTREME v2 (with 83e3c48729d9 and a0b1280368d1) 4.15+

 + *   vmcoreinfo: address of mem_section root array

 + *   -x vmlinux: address of pointer to mem_section root array

 + */

  static int

  get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,

  		unsigned int num_section)

 @@ -3710,12 +3726,27 @@ get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,

  		    strerror(errno));

  		return FALSE;

  	}

 +

 +	/*

 +	 * There was a report that the first validation wrongly returned TRUE

 +	 * with -x vmlinux and SPARSEMEM_EXTREME v2 on s390x, so skip it.

 +	 * Howerver, leave the fallback validation as it is for the -i option.

 +	 */

 +	if (is_sparsemem_extreme() && info->name_vmlinux) {

 +		unsigned long flag = 0;

 +		if (get_symbol_type_name("mem_section", DWARF_INFO_GET_SYMBOL_TYPE,

 +					NULL, &flag)

 +		    && !(flag & TYPE_ARRAY))

 +			goto skip_1st_validation;

 +	}

 +

  	ret = validate_mem_section(mem_sec, SYMBOL(mem_section),

  				   mem_section_size, mem_maps, num_section);

  	if (!ret && is_sparsemem_extreme()) {

  		unsigned long mem_section_ptr;

 +skip_1st_validation:

  		if (!readmem(VADDR, SYMBOL(mem_section), &mem_section_ptr,

  			     sizeof(mem_section_ptr)))

  			goto out;