From: Stefan Berger stefanb@linux.ibm.com

stable inclusion from stable-v5.10.209 commit 3b8d7a1b851918cc3529a38a271c7a0ea8ad1217 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9FP1N CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 21528c69a0d8483f7c6345b1a0bc8d8975e9a172 upstream.

Documentation/filesystems/ramfs-rootfs-initramfs.rst states:

If CONFIG_TMPFS is enabled, rootfs will use tmpfs instead of ramfs by default. To force ramfs, add "rootfstype=ramfs" to the kernel command line.

This currently does not work when root= is provided since then saved_root_name contains a string and rootfstype= is ignored. Therefore, ramfs is currently always chosen when root= is provided.

The current behavior for rootfs's filesystem is:

root= | rootfstype= | chosen rootfs filesystem ------------+-------------+-------------------------- unspecified | unspecified | tmpfs unspecified | tmpfs | tmpfs unspecified | ramfs | ramfs provided | ignored | ramfs

rootfstype= should be respected regardless whether root= is given, as shown below:

root= | rootfstype= | chosen rootfs filesystem ------------+-------------+-------------------------- unspecified | unspecified | tmpfs (as before) unspecified | tmpfs | tmpfs (as before) unspecified | ramfs | ramfs (as before) provided | unspecified | ramfs (compatibility with before) provided | tmpfs | tmpfs (new) provided | ramfs | ramfs (new)

This table represents the new behavior.

Fixes: 6e19eded3684 ("initmpfs: use initramfs if rootfstype= or root= specified") Cc: stable@vger.kernel.org Signed-off-by: Rob Landley rob@landley.net Link: https://lore.kernel.org/lkml/8244c75f-445e-b15b-9dbf-266e7ca666e2@landley.ne... Reviewed-and-Tested-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: Stefan Berger stefanb@linux.ibm.com Link: https://lore.kernel.org/r/20231120011248.396012-1-stefanb@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Conflicts: init/do_mounts.c Signed-off-by: GUO Zihua guozihua@huawei.com --- init/do_mounts.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/init/do_mounts.c b/init/do_mounts.c index 69bdd953ba87..178e37340a23 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -527,9 +527,14 @@ void __init init_rootfs(void) #ifdef CONFIG_IMA_DIGEST_LIST if (IS_ENABLED(CONFIG_TMPFS) && (!saved_root_name[0] || initramtmpfs) && +- (!root_fs_names || strstr(root_fs_names, "tmpfs"))) +- is_tmpfs = true; #else - if (IS_ENABLED(CONFIG_TMPFS) && !saved_root_name[0] && + if (IS_ENABLED(CONFIG_TMPFS)) { + if (!saved_root_name[0] && !root_fs_names) + is_tmpfs = true; + else if (root_fs_names && !!strstr(root_fs_names, "tmpfs")) + is_tmpfs = true; + } #endif - (!root_fs_names || strstr(root_fs_names, "tmpfs"))) - is_tmpfs = true; }