cp: pass the directory to tar via -C instead of the working directory - #5238
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GNU tar 1.30-13.el8_10 (AlmaLinux 8, released 2026-09-18) aborts with
"Cannot getcwd: No such file or directory" when its working directory
is under /proc/<pid>/root of a container, as the path is unreachable
from the host mount namespace (the kernel returns "(unreachable)/...",
and glibc turns it into ENOENT).
The regression comes from the combination of two upstream tar commits
as backported to RHEL/AlmaLinux 8's tar 1.30:
- 56fb4a96 ("chdir_id refactoring"), backported in 1.30-12 as part of
the CVE-2025-45582 fix, introduced grow_wd(). Upstream initializes
wd[0].abspath lazily (NULL), but the 1.30 backport keeps calling
xgetcwd() eagerly and fails fatally on error.
- 1b91f5f6 ("Draft patch for openat2 changes vs --one-top-level"),
backported in 1.30-13, adds an unconditional
`chdir_do (chdir_arg (".", ...), false)` to name_init(), so
grow_wd() (and thus getcwd) is now reached on every invocation,
not only when -C is specified.
AlmaLinux 8 went from 1.30-11 directly to 1.30-13.
Upstream tar is not affected (getcwd is lazy there), and neither commit
is in an upstream release as of v1.35.
Using `-C <dir>` keeps the tar process's working directory on the host
while tar opens the directory by itself.
As the tar process no longer chdirs into the extraction directory, an
inaccessible destination is now checked with access(2) beforehand, so
that it is still reported as ErrTargetIsReadOnly.
Fixes containerd#5237 (the `nerdctl cp` part)
Assisted-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
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GNU tar 1.30-13.el8_10 (AlmaLinux 8, released 2026-09-18) aborts with "Cannot getcwd: No such file or directory" when its working directory is under /proc//root of a container, as the path is unreachable from the host mount namespace (the kernel returns "(unreachable)/...", and glibc turns it into ENOENT).
The regression comes from the combination of two upstream tar commits as backported to RHEL/AlmaLinux 8's tar 1.30:
56fb4a96 ("chdir_id refactoring"), backported in 1.30-12 as part of the CVE-2025-45582 fix, introduced grow_wd(). Upstream initializes wd[0].abspath lazily (NULL), but the 1.30 backport keeps calling xgetcwd() eagerly and fails fatally on error.
1b91f5f6 ("Draft patch for openat2 changes vs --one-top-level"), backported in 1.30-13, adds an unconditional
chdir_do (chdir_arg (".", ...), false)to name_init(), so grow_wd() (and thus getcwd) is now reached on every invocation, not only when -C is specified.AlmaLinux 8 went from 1.30-11 directly to 1.30-13. Upstream tar is not affected (getcwd is lazy there), and neither commit is in an upstream release as of v1.35.
Using
-C <dir>keeps the tar process's working directory on the host while tar opens the directory by itself.Fixes #5237 (the
nerdctl cppart)Assisted-by: Claude Opus 5.5 (1M context) noreply@anthropic.com