This bug was fixed in the package linux - 5.4.0-42.46
---------------
linux (5.4.0-42.46) focal; urgency=medium
* focal/linux: 5.4.0-42.46 -proposed tracker (LP: #1887069)
* linux 4.15.0-109-generic network DoS regression vs -108 (LP: #1886668)
- SAUCE: Revert "netprio_cgroup: Fix unlimited memory leak of v2 cgroups"
linux (5.4.0-41.45) focal; urgency=medium
* focal/linux: 5.4.0-41.45 -proposed tracker (LP: #1885855)
* Packaging resync (LP: #1786013)
- update dkms package versions
* CVE-2019-19642
- kernel/relay.c: handle alloc_percpu returning NULL in relay_open
* CVE-2019-16089
- SAUCE: nbd_genl_status: null check for nla_nest_start
* CVE-2020-11935
- aufs: do not call i_readcount_inc()
* ip_defrag.sh in net from ubuntu_kernel_selftests failed with 5.0 / 5.3 / 5.4
kernel (LP: #1826848)
- selftests: net: ip_defrag: ignore EPERM
* Update lockdown patches (LP: #1884159)
- SAUCE: acpi: disallow loading configfs acpi tables when locked down
* seccomp_bpf fails on powerpc (LP: #1885757)
- SAUCE: selftests/seccomp: fix ptrace tests on powerpc
* Introduce the new NVIDIA 418-server and 440-server series, and update the
current NVIDIA drivers (LP: #1881137)
- [packaging] add signed modules for the 418-server and the 440-server
flavours
-- Khalid Elmously <[email protected]> Thu, 09 Jul 2020
19:50:26 -0400
** Changed in: linux (Ubuntu)
Status: Fix Committed => Fix Released
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-16089
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2019-19642
** CVE added: https://cve.mitre.org/cgi-bin/cvename.cgi?name=2020-11935
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https://bugs.launchpad.net/bugs/1872757
Title:
shiftfs: O_TMPFILE reports ESTALE
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Eoan:
Fix Released
Status in linux source package in Focal:
Fix Released
Bug description:
SRU Justification
Impact: Christian Kellner reported that creating temporary files via
O_TMPFILE shiftfs reports ESTALE. This can be reproduced via:
import tempfile
import os
def test():
with tempfile.TemporaryFile() as fd:
fd.write("data".encode('utf-8'))
# re-open the file to get a read-only file descriptor
return open(f"/proc/self/fd/{fd.fileno()}", "r")
def main():
fd = test()
fd.close()
if __name__ == "__main__":
main()
a similar issue was reported here:
https://github.com/systemd/systemd/issues/14861
Fix: Our revalidate methods were very opinionated about whether or not
a dentry was valid when we really should've just let the underlay tell
us what's what. This has led to bugs where a ESTALE was returned for
e.g. temporary files that were created and directly re-opened
afterwards through /proc/<pid>/fd/<nr-of-deleted-file>. When a file is
re-opened through /proc/<pid>/fd/<nr> LOOKUP_JUMP is set and the vfs
will revalidate via d_weak_revalidate(). Since the file has been
unhashed or even already gone negative we'd fail the open when we
should've succeeded.
I had also foolishly provided a .tmpfile method which so far only has
caused us trouble. If we really need this then we can reimplement it
properly but I doubt it. Remove it for now.
Regression Potential: Limited to shiftfs.
Test Case: Build a kernel with fix applied and run above reproducer.
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