initramfs: use scoped_with_init_fs() for rootfs unpacking

Extract the initramfs unpacking code into a separate
unpack_initramfs() function and wrap its invocation from
do_populate_rootfs() with scoped_with_init_fs(). This ensures all
file operations during initramfs unpacking (including filp_open()
calls in do_name() and populate_initrd_image()) happen in init's
filesystem context.

Note that security_initramfs_populated() needs the scope as well since
it does use current->fs to derive the initramfs superblock.

do_populate_rootfs() ← async_schedule_domain() ← kworker (async
workqueue)

May also run synchronously from PID 1 in case async workqueue is
considered full. Overriding in that case is fine as well.

Link: https://patch.msgid.link/20260601-work-kthread-nullfs-v4-17-77ee053060e0@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2026-06-01 15:56:50 +02:00
parent ba2e078299
commit d0f102fce3

View File

@@ -6,6 +6,7 @@
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/fs_struct.h>
#include <linux/hex.h>
#include <linux/init.h>
#include <linux/init_syscalls.h>
@@ -716,7 +717,7 @@ static void __init populate_initrd_image(char *err)
}
#endif /* CONFIG_BLK_DEV_RAM */
static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
static void __init unpack_initramfs(async_cookie_t cookie)
{
/* Load the built in initramfs */
char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
@@ -724,7 +725,7 @@ static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
goto done;
return;
if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
@@ -739,9 +740,14 @@ static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
#endif
}
}
done:
security_initramfs_populated();
static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
{
scoped_with_init_fs() {
unpack_initramfs(cookie);
security_initramfs_populated();
}
/*
* If the initrd region is overlapped with crashkernel reserved region,