[Bug 1774216] [NEW] gdb incorrectly performs modulo 32 on 64 bit operands for 'x' command

[George Shuklin]

Public bug reported:

https://stackoverflow.com/questions/50607748/how-to-force-gdb-to-view-
at-a-given-address

$ gdb

(gdb) x 0x7f3ca4f68c20
0xa4f68c20: Cannot access memory at address 0xa4f68c20

Actual results: Attemp to read a value from 0xa4f68c20
Expected results: attempt to read a value from 0x7f3ca4f68c20.

This bug is present in GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
(bionic)

This bug does not present in GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5)
7.11.1 (xenial)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gdb 8.1-0ubuntu3
ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
Uname: Linux 4.15.0-22-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
CurrentDesktop: X-Cinnamon
Date: Wed May 30 18:20:11 2018
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-xenial-amd64-20160624-2
EcryptfsInUse: Yes
InstallationDate: Installed on 2017-06-22 (342 days ago)
InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
SourcePackage: gdb
UpgradeStatus: No upgrade log present (probably fresh install)

** Affects: gdb (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug bionic

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https://bugs.launchpad.net/bugs/1774216

Title:
  gdb incorrectly performs modulo 32 on 64 bit operands for 'x' command

Status in gdb package in Ubuntu:
  New

Bug description:
  https://stackoverflow.com/questions/50607748/how-to-force-gdb-to-view-
  at-a-given-address

  $ gdb

  (gdb) x 0x7f3ca4f68c20
  0xa4f68c20: Cannot access memory at address 0xa4f68c20

  Actual results: Attemp to read a value from 0xa4f68c20
  Expected results: attempt to read a value from 0x7f3ca4f68c20.

  This bug is present in GNU gdb (Ubuntu 8.1-0ubuntu3)
  8.1.0.20180409-git (bionic)

  This bug does not present in GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5)
  7.11.1 (xenial)

  ProblemType: Bug
  DistroRelease: Ubuntu 18.04
  Package: gdb 8.1-0ubuntu3
  ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
  Uname: Linux 4.15.0-22-generic x86_64
  ApportVersion: 2.20.9-0ubuntu7
  Architecture: amd64
  CurrentDesktop: X-Cinnamon
  Date: Wed May 30 18:20:11 2018
  DistributionChannelDescriptor:
   # This is a distribution channel descriptor
   # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
   canonical-oem-somerville-xenial-amd64-20160624-2
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2017-06-22 (342 days ago)
  InstallationMedia: Ubuntu 16.04 "Xenial" - Build amd64 LIVE Binary 20160624-10:47
  SourcePackage: gdb
  UpgradeStatus: No upgrade log present (probably fresh install)

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