Resolve null-dereference and enable Linux containers #9622
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After initial for-loop best might be 0x0. The patch avoids NULL-dereference issue, which causes segfaults. Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch> Reported-by: Sébastien Brochet <sebastien.brochet@cern.ch>
According to glibc documentation one should use `_PATH_MOUNTED`, which by default should point to `/etc/mtab`. This file is maintained by `mount` and `umount` programs. This is wrong if we are running in a sandboxed everinment, e.g. Linux containers (OpenVZ, Docker, Rocket, LXC/LXD) or chroot/proot. Then this files comes from alternative rootfs and does not reflect actual mount points. On modern systems (incl. CentOS 7 and Fedora) `/etc/mtab` points to `/proc/self/mounts`. The patch by default reads `/proc/self/mounts` on Linux systems. By default Docker will create a `/etc/mtab` as symlink to `/proc/mounts` (which points to `/proc/self/mounts`) on any container. OpenVZ documentation also request chaging `/etc/mtab` to a symlink. Same in Linux From Scratch guide. Also reminds that `/` could be mounted as read-only, thus `/etc/mtab` could be stale. Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch> Reported-by: Sébastien Brochet <sebastien.brochet@cern.ch>
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A new Pull Request was created by @davidlt for CMSSW_7_4_X. Resolve null-dereference and enable Linux containers It involves the following packages: Utilities/StorageFactory @cmsbuild, @Dr15Jones can you please review it and eventually sign? Thanks. |
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please test |
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+1 |
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The tests are being triggered in jenkins. |
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This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs once checked with relvals in the development release cycle of CMSSW or unless it breaks tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar |
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This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs once checked with relvals in the development release cycle of CMSSW (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar |
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This pull request is fully signed and it will be integrated in one of the next CMSSW_7_4_X IBs once checked with relvals in the development release cycle of CMSSW (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar |
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+1 |
Resolve null-dereference and enable Linux containers
Notice: commit messages contains more information.
CMSSW fails on at least one site where Linux containers are used (probably instead of virtual machines). You cannot trust
/etc/mtabcontent, go directly for/proc/self/mounts.Same issue happens if CMSSW is compiled with ASan, in this case
realpathwas not doing a correct job for ".". Could be a bug in ASan interceptor.Same PR approved for CMSSW_7_5_X: #9541