Public bug reported:
The following fixes were backported to bionic and xenial to prevent a
potential security issue:
- Make filldir[64]() verify the directory entry filename is valid
- filldir[64]: remove WARN_ON_ONCE() for bad directory entries
In that process, they introduced a potential performace impact on
readdir. How much is yet to be measured.
9f79b78ef74436c7507bac6bfb7b8b989263bccb Convert filldir[64]() from
__put_user() to unsafe_put_user()
c512c69187197fe08026cb5bbe7b9709f4f89b73 uaccess: implement a proper
unsafe_copy_to_user() and switch filldir over to it
The two commits above try to mitigate that performance impact. At least
on x86 with SMAP, that should have some effect. At any other platforms,
at least on bionic and xenial, any improvements should be measured.
Though that is true for x86 with SMAP too.
This bug is opened in order to keep track of that possible performance
improvement we might add in the future as followup for those two
commits.
Cascardo.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: Fix Released
** Affects: linux (Ubuntu Xenial)
Importance: Low
Status: Triaged
** Affects: linux (Ubuntu Bionic)
Importance: Low
Assignee: Thadeu Lima de Souza Cascardo (cascardo)
Status: In Progress
** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
** No longer affects: kernel-sru-workflow
** Also affects: linux (Ubuntu Bionic)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu Xenial)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Xenial)
Status: New => In Progress
** Changed in: linux (Ubuntu Bionic)
Status: New => In Progress
** Changed in: linux (Ubuntu Xenial)
Status: In Progress => Triaged
** Changed in: linux (Ubuntu Bionic)
Assignee: (unassigned) => Thadeu Lima de Souza Cascardo (cascardo)
** Changed in: linux (Ubuntu Bionic)
Importance: Undecided => Low
** Changed in: linux (Ubuntu Xenial)
Importance: Undecided => Low
** Changed in: linux (Ubuntu)
Status: New => Fix Released
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https://bugs.launchpad.net/bugs/1881339
Title:
readdir performance when copying to userspace
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