mirror of
https://github.com/torvalds/linux.git
synced 2026-03-08 05:24:39 +01:00
Linux kernel source tree
225034cd51
Covered in Documentation/driver-api/early-userspace/buffer-format.rst ,
initramfs archives can carry an optional "TRAILER!!!" entry which serves
as a boundary for collecting and associating hardlinks with matching
inode and major / minor device numbers.
Although optional, if hardlinks are found in an archive without a
subsequent "TRAILER!!!" entry then the hardlink state hash table is
leaked, e.g. unfixed kernel, with initramfs_test.c hunk applied only:
unreferenced object 0xffff9405408cc000 (size 8192):
comm "kunit_try_catch", pid 53, jiffies 4294892519
hex dump (first 32 bytes):
01 00 00 00 01 00 00 00 00 00 00 00 ff 81 00 00 ................
00 00 00 00 00 00 00 00 69 6e 69 74 72 61 6d 66 ........initramf
backtrace (crc a9fb0ee0):
[<0000000066739faa>] __kmalloc_cache_noprof+0x11d/0x250
[<00000000fc755219>] maybe_link.part.5+0xbc/0x120
[<000000000526a128>] do_name+0xce/0x2f0
[<00000000145c1048>] write_buffer+0x22/0x40
[<000000003f0b4f32>] unpack_to_rootfs+0xf9/0x2a0
[<00000000d6f7e5af>] initramfs_test_hardlink+0xe3/0x3f0
[<0000000014fde8d6>] kunit_try_run_case+0x5f/0x130
[<00000000dc9dafc5>] kunit_generic_run_threadfn_adapter+0x18/0x30
[<000000001076c239>] kthread+0xc8/0x100
[<00000000d939f1c1>] ret_from_fork+0x2b/0x40
[<00000000f848ad1a>] ret_from_fork_asm+0x1a/0x30
Fix this by calling free_hash() after initramfs buffer processing in
unpack_to_rootfs(). An extra hardlink_seen global is added as an
optimization to avoid walking the 32 entry hash array unnecessarily.
The expectation is that a "TRAILER!!!" entry will normally be present,
and initramfs hardlinks are uncommon.
There is one user facing side-effect of this fix: hardlinks can
currently be associated across built-in and external initramfs archives,
*if* the built-in initramfs archive lacks a "TRAILER!!!" terminator. I'd
consider this cross-archive association broken, but perhaps it's used.
Signed-off-by: David Disseldorp <ddiss@suse.de>
Link: https://lore.kernel.org/r/20250304061020.9815-8-ddiss@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.