[Makedumpfile PATCH v4 0/2] Fix refiltering when kaslr enabled

Pratyush Anand panand at redhat.com
Thu May 25 20:06:38 PDT 2017

Hi All,

We came across another failure in makedumpfile when kaslr is enabled. This
failure occurs when we try re-filtering. We try to erase some symbol from a
dumpfile which was copied/compressed from /proc/vmcore using makedumpfile.

We have very limited symbol information in vmcoreinfo. So symbols to be
erased may not be available in vmcoreinfo and we look for it in vmlinux.
However,  symbol address from vmlinux is a static address which differs
from run time address with KASLR_OFFSET. Therefore, reading any "virtual
address of vmlinux" from vmcore is not possible. 

These patches finds runtime  KASLR offset and then calculates run time
address of symbols read from vmlinux.

Hatayama Daisuke also found some issue [1] when he was working with a
sadump and virsh dump of a none kaslr kernel. Patch 2/2 of this series has
been improved to take care of those issues as well.




 - reading KERNELOFFSET from vmcoreinfo now instead of calculating it from
 - Fixed initialization of info->file_vmcoreinfo
 - Improved page_offset calculation logic to take care of different dump
 - Removed info->kaslr_offset write to VMCOREINFO

Pratyush Anand (2):
  makedumpfile: add runtime kaslr offset if it exists
  x86_64: calculate page_offset in case of re-filtering/sadump/virsh

 arch/x86_64.c  | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++------
 erase_info.c   |  1 +
 makedumpfile.c | 46 +++++++++++++++++++++++++++++++++++++
 makedumpfile.h | 16 +++++++++++++
 4 files changed, 128 insertions(+), 7 deletions(-)


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