From a6eccc3647c167ba13ac23885a8ea787f44d97e5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Wed, 2 Nov 2016 22:05:06 -0400 Subject: [PATCH] Do not raise in switch root if paths are too long If we encounter the (unlikely) situation where the combined path to the new root and a path to a mount to be moved together exceed maximum path length, we shouldn't crash, but fail this path instead. --- src/shared/switch-root.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/src/shared/switch-root.c b/src/shared/switch-root.c index 47d3a5a1fa2..4eff4f692e0 100644 --- a/src/shared/switch-root.c +++ b/src/shared/switch-root.c @@ -75,17 +75,29 @@ int switch_root(const char *new_root, const char *oldroot, bool detach_oldroot, NULSTR_FOREACH(i, move_mounts) { char new_mount[PATH_MAX]; struct stat sb; + size_t n; - xsprintf(new_mount, "%s%s", new_root, i); + n = snprintf(new_mount, sizeof new_mount, "%s%s", new_root, i); + if (n >= sizeof new_mount) { + bool move = mountflags & MS_MOVE; + + log_warning("New path is too long, %s: %s%s", + move ? "forcing unmount instead" : "ignoring", + new_root, i); + + if (move) + if (umount2(i, MNT_FORCE) < 0) + log_warning_errno(errno, "Failed to unmount %s: %m", i); + continue; + } mkdir_p_label(new_mount, 0755); - if ((stat(new_mount, &sb) < 0) || + if (stat(new_mount, &sb) < 0 || sb.st_dev != new_root_stat.st_dev) { /* Mount point seems to be mounted already or - * stat failed. Unmount the old mount - * point. */ + * stat failed. Unmount the old mount point. */ if (umount2(i, MNT_DETACH) < 0) log_warning_errno(errno, "Failed to unmount %s: %m", i); continue; @@ -97,10 +109,9 @@ int switch_root(const char *new_root, const char *oldroot, bool detach_oldroot, if (umount2(i, MNT_FORCE) < 0) log_warning_errno(errno, "Failed to unmount %s: %m", i); - } - if (mountflags & MS_BIND) - log_error_errno(errno, "Failed to bind mount %s to %s: %m", i, new_mount); + } else if (mountflags & MS_BIND) + log_error_errno(errno, "Failed to bind mount %s to %s: %m", i, new_mount); } }