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| author | Steev Klimaszewski | 2026-01-17 04:10:22 +0000 |
|---|---|---|
| committer | Daniel Golle | 2026-03-14 00:29:08 +0000 |
| commit | 6dafa862b16cc3dcd1ea7d67febc444b51aed3e2 (patch) | |
| tree | ada3b6c756085f54d25aa90ef157c9978efd296e | |
| parent | c268f13ab8b8e60d69aabc9ee42b9c0b7d191ed5 (diff) | |
| download | procd-6dafa862b16cc3dcd1ea7d67febc444b51aed3e2.tar.gz | |
initd/coldplug: create /dev/null before running udevtrigger
When procd_coldplug() runs, it unmounts /dev and mounts a fresh empty
tmpfs before forking udevtrigger to populate device nodes via hotplug
events. Since udevtrigger runs asynchronously, there is a race window
between the fresh mount and when the "null" device uevent is processed.
If any code executes a shell redirect to /dev/null during this window
(e.g., from hotplug handlers or other event processing), the shell
creates /dev/null as a regular file. When the null device uevent is
later processed, makedev()'s mknod() fails silently with EEXIST,
leaving /dev/null as a regular file permanently.
This causes all subsequent redirections to /dev/null to append to the
file instead of discarding output, eventually filling up the tmpfs.
Fix by explicitly creating /dev/null immediately after mounting the
fresh tmpfs, before any other code can run.
Signed-off-by: Steev Klimaszewski <threeway@gmail.com>
(cherry picked from commit 58d7aaa686979eb852139915a30df33adcb08665)
| -rw-r--r-- | plug/coldplug.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/plug/coldplug.c b/plug/coldplug.c index f84acef..1925402 100644 --- a/plug/coldplug.c +++ b/plug/coldplug.c @@ -49,6 +49,7 @@ void procd_coldplug(void) umount2("/dev/pts", MNT_DETACH); umount2("/dev/", MNT_DETACH); mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=0755,size=512K"); + mknod("/dev/null", S_IFCHR | 0666, makedev(1, 3)); mkdir("/dev/pts", 0755); mount("devpts", "/dev/pts", "devpts", MS_NOATIME | MS_NOEXEC | MS_NOSUID, 0); } |