[1.4] Fix runc exec vs go1.26 + older kernel#5116
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kolyshkin merged 3 commits intoopencontainers:release-1.4from Feb 12, 2026
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[1.4] Fix runc exec vs go1.26 + older kernel#5116kolyshkin merged 3 commits intoopencontainers:release-1.4from
kolyshkin merged 3 commits intoopencontainers:release-1.4from
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Theoretically, exec.Command can set cmd.Err. Practically, this should never happen (Linux, Go <= 1.26, exePath is absolute), but in the unlikely case it does, let's fail early. This is related to the cloneCmd (to be introduced by the following commit) which chooses to not copy the Err field. Theoretically, exec.Command can set Err and so the first call to cmd.Start will fail (since Err != nil), and the second call to cmd.Start may succeed because Err == nil. Yet, this scenario is highly unlikely, but better be safe than sorry. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit 82b7597) Signed-off-by: lifubang <lifubang@acmcoder.com>
Since [PR 4812], runc exec tries to use clone3 syscall with CLONE_INTO_CGROUP, falling back to the old method if it is not supported. One issue with that approach is, a > Cmd cannot be reused after calling its [Cmd.Start], [Cmd.Run], > [Cmd.Output], or [Cmd.CombinedOutput] methods. (from https://pkg.go.dev/os/exec#Cmd). This is enforced since Go 1.26, see [CL 728642], and so runc exec actually fails in specific scenarios (go1.26 and no CLONE_INTO_CGROUP support). The easiest workaround is to pre-copy the p.cmd structure (copy = *cmd). From the [CL 734200] it looks like it is an acceptable way, but it might break in the future as it also copies the private fields, so let's do a proper field-by-field copy. If the upstream will add cmd.Clone method, we will switch to it. Also, we can probably be fine with a post-copy (once the first Start has failed), but let's be conservative here and do a pre-copy. [PR 4812]: opencontainers#4812 [CL 728642]: https://go.dev/cl/728642 [CL 734200]: https://go.dev/cl/734200 Reported-by: Efim Verzakov <efimverzakov@gmail.com> Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit cb31d62) Signed-off-by: lifubang <lifubang@acmcoder.com>
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Feb 11, 2026
This commit is a squash of the following two commits: 1. ci: add go 1.26 rc2 This is mostly to test whether https://go.dev/cl/728642 results in any test failures in the current CI matrix. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit e4e0542) Signed-off-by: lifubang <lifubang@acmcoder.com> 2. ci: bump Go 1.26rc2 -> 1.26.x Since Go 1.26.0 is released today. Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit daa5ffc) Signed-off-by: lifubang <lifubang@acmcoder.com>
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Haha, I swear I saw this backport happen in a parallel universe where I actually read the PRs before merging. 🥲 Guess I’ll just go ahead and squash it like a time-traveling commit from an alternate reality. |
kolyshkin
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Feb 12, 2026
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Backport #5091 and #5109
Since PR 4812, runc exec tries to use
clone3syscall withCLONE_INTO_CGROUP, falling back to the old method if it is notsupported.
One issue with that approach is, a
(from https://pkg.go.dev/os/exec#Cmd).
This is enforced since Go 1.26, see CL 728642, and so runc exec
actually fails in specific scenarios (go1.26 and no CLONE_INTO_CGROUP
support).
The easiest workaround is to pre-copy the p.cmd structure. From the
CL 734200 it looks like it is an acceptable way. If the upstream
will introduce cmd.Clone we'll switch to it.
As for the test case, it looks like adding Go 1.26 to the testing
matrix is sufficient to reveal the issue (some tests involving
runc execfail with Go 1.26 before the fix).