linux.git/lib/bootconfig.c, branch v6.18.21

lib/bootconfig: check xbc_init_node() return in override path

2026-03-25T10:10:45+00:00

[ Upstream commit bb288d7d869e86d382f35a0e26242c5ccb05ca82 ]

The ':=' override path in xbc_parse_kv() calls xbc_init_node() to
re-initialize an existing value node but does not check the return
value. If xbc_init_node() fails (data offset out of range), parsing
silently continues with stale node data.

Add the missing error check to match the xbc_add_node() call path
which already checks for failure.

In practice, a bootconfig using ':=' to override a value near the
32KB data limit could silently retain the old value, meaning a
security-relevant boot parameter override (e.g., a trace filter or
debug setting) would not take effect as intended.

Link: https://lore.kernel.org/all/20260318155847.78065-2-objecting@objecting.org/

Fixes: e5efaeb8a8f5 ("bootconfig: Support mixing a value and subkeys under a key")
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Sasha Levin

lib/bootconfig: check bounds before writing in __xbc_open_brace()

2026-03-19T15:08:45+00:00

commit 560f763baa0f2c9a44da4294c06af071405ac46f upstream.

The bounds check for brace_index happens after the array write.
While the current call pattern prevents an actual out-of-bounds
access (the previous call would have returned an error), the
write-before-check pattern is fragile and would become a real
out-of-bounds write if the error return were ever not propagated.

Move the bounds check before the array write so the function is
self-contained and safe regardless of caller behavior.

Link: https://lore.kernel.org/all/20260312191143.28719-3-objecting@objecting.org/

Fixes: ead1e19ad905 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

lib/bootconfig: fix snprintf truncation check in xbc_node_compose_key_after()

2026-03-19T15:08:44+00:00

commit 1120a36bb1e9b9e22de75ecb4ef0b998f73a97f1 upstream.

snprintf() returns the number of characters that would have been
written excluding the NUL terminator.  Output is truncated when the
return value is >= the buffer size, not just > the buffer size.

When ret == size, the current code takes the non-truncated path,
advancing buf by ret and reducing size to 0.  This is wrong because
the output was actually truncated (the last character was replaced by
NUL).  Fix by using >= so the truncation path is taken correctly.

Link: https://lore.kernel.org/all/20260312191143.28719-4-objecting@objecting.org/

Fixes: 76db5a27a827 ("bootconfig: Add Extra Boot Config support")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

lib/bootconfig: fix off-by-one in xbc_verify_tree() unclosed brace error

2026-03-19T15:08:44+00:00

commit 39ebc8d7f561e1b64eca87353ef9b18e2825e591 upstream.

__xbc_open_brace() pushes entries with post-increment
(open_brace[brace_index++]), so brace_index always points one past
the last valid entry.  xbc_verify_tree() reads open_brace[brace_index]
to report which brace is unclosed, but this is one past the last
pushed entry and contains stale/zero data, causing the error message
to reference the wrong node.

Use open_brace[brace_index - 1] to correctly identify the unclosed
brace.  brace_index is known to be > 0 here since we are inside the
if (brace_index) guard.

Link: https://lore.kernel.org/all/20260312191143.28719-2-objecting@objecting.org/

Fixes: ead1e19ad905 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law 
Reviewed-by: Steven Rostedt (Google) 
Signed-off-by: Masami Hiramatsu (Google) 
Signed-off-by: Greg Kroah-Hartman

bootconfig: Remove duplicate included header file linux/bootconfig.h

2024-07-11T23:55:02+00:00

The header file linux/bootconfig.h is included whether __KERNEL__ is
defined or not.

Include it only once before the #ifdef/#else/#endif preprocessor
directives and remove the following make includecheck warning:

  linux/bootconfig.h is included more than once

Move the comment to the top and delete the now empty #else block.

Link: https://lore.kernel.org/all/20240711084315.1507-1-thorsten.blum@toblux.com/

Signed-off-by: Thorsten Blum 
Signed-off-by: Masami Hiramatsu (Google)

bootconfig: Fix the kerneldoc of _xbc_exit()

2024-04-17T20:01:32+00:00

Fix the kerneldoc of _xbc_exit() which is updated to have an @early
argument and the function name is changed.

Link: https://lore.kernel.org/all/171321744474.599864.13532445969528690358.stgit@devnote2/

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202404150036.kPJ3HEFA-lkp@intel.com/
Fixes: 89f9a1e876b5 ("bootconfig: use memblock_free_late to free xbc memory to buddy")
Signed-off-by: Masami Hiramatsu (Google)

bootconfig: use memblock_free_late to free xbc memory to buddy

2024-04-14T13:00:43+00:00

On the time to free xbc memory in xbc_exit(), memblock may has handed
over memory to buddy allocator. So it doesn't make sense to free memory
back to memblock. memblock_free() called by xbc_exit() even causes UAF bugs
on architectures with CONFIG_ARCH_KEEP_MEMBLOCK disabled like x86.
Following KASAN logs shows this case.

This patch fixes the xbc memory free problem by calling memblock_free()
in early xbc init error rewind path and calling memblock_free_late() in
xbc exit path to free memory to buddy allocator.

[    9.410890] ==================================================================
[    9.418962] BUG: KASAN: use-after-free in memblock_isolate_range+0x12d/0x260
[    9.426850] Read of size 8 at addr ffff88845dd30000 by task swapper/0/1

[    9.435901] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G     U             6.9.0-rc3-00208-g586b5dfb51b9 #5
[    9.446403] Hardware name: Intel Corporation RPLP LP5 (CPU:RaptorLake)/RPLP LP5 (ID:13), BIOS IRPPN02.01.01.00.00.19.015.D-00000000 Dec 28 2023
[    9.460789] Call Trace:
[    9.463518]  
[    9.465859]  dump_stack_lvl+0x53/0x70
[    9.469949]  print_report+0xce/0x610
[    9.473944]  ? __virt_addr_valid+0xf5/0x1b0
[    9.478619]  ? memblock_isolate_range+0x12d/0x260
[    9.483877]  kasan_report+0xc6/0x100
[    9.487870]  ? memblock_isolate_range+0x12d/0x260
[    9.493125]  memblock_isolate_range+0x12d/0x260
[    9.498187]  memblock_phys_free+0xb4/0x160
[    9.502762]  ? __pfx_memblock_phys_free+0x10/0x10
[    9.508021]  ? mutex_unlock+0x7e/0xd0
[    9.512111]  ? __pfx_mutex_unlock+0x10/0x10
[    9.516786]  ? kernel_init_freeable+0x2d4/0x430
[    9.521850]  ? __pfx_kernel_init+0x10/0x10
[    9.526426]  xbc_exit+0x17/0x70
[    9.529935]  kernel_init+0x38/0x1e0
[    9.533829]  ? _raw_spin_unlock_irq+0xd/0x30
[    9.538601]  ret_from_fork+0x2c/0x50
[    9.542596]  ? __pfx_kernel_init+0x10/0x10
[    9.547170]  ret_from_fork_asm+0x1a/0x30
[    9.551552]  

[    9.555649] The buggy address belongs to the physical page:
[    9.561875] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x45dd30
[    9.570821] flags: 0x200000000000000(node=0|zone=2)
[    9.576271] page_type: 0xffffffff()
[    9.580167] raw: 0200000000000000 ffffea0011774c48 ffffea0012ba1848 0000000000000000
[    9.588823] raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
[    9.597476] page dumped because: kasan: bad access detected

[    9.605362] Memory state around the buggy address:
[    9.610714]  ffff88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[    9.618786]  ffff88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[    9.626857] >ffff88845dd30000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[    9.634930]                    ^
[    9.638534]  ffff88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[    9.646605]  ffff88845dd30100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[    9.654675] ==================================================================

Link: https://lore.kernel.org/all/20240414114944.1012359-1-qiang4.zhang@linux.intel.com/

Fixes: 40caa127f3c7 ("init: bootconfig: Remove all bootconfig data when the init memory is removed")
Cc: Stable@vger.kernel.org
Signed-off-by: Qiang Zhang 
Acked-by: Masami Hiramatsu (Google) 
Signed-off-by: Masami Hiramatsu (Google)

bootconfig: Support embedding a bootconfig file in kernel

2022-04-26T21:58:51+00:00

This allows kernel developer to embed a default bootconfig file in
the kernel instead of embedding it in the initrd. This will be good
for who are using the kernel without initrd, or who needs a default
bootconfigs.
This needs to set two kconfigs: CONFIG_BOOT_CONFIG_EMBED=y and set
the file path to CONFIG_BOOT_CONFIG_EMBED_FILE.

Note that you still need 'bootconfig' command line option to load the
embedded bootconfig. Also if you boot using an initrd with a different
bootconfig, the kernel will use the bootconfig in the initrd, instead
of the default bootconfig.

Link: https://lkml.kernel.org/r/164921227943.1090670.14035119557571329218.stgit@devnote2

Cc: Padmanabha Srinivasaiah 
Cc: Jonathan Corbet 
Cc: Randy Dunlap 
Cc: Nick Desaulniers 
Cc: Sami Tolvanen 
Cc: Nathan Chancellor 
Cc: Masahiro Yamada 
Cc: Linux Kbuild mailing list 
Signed-off-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (Google)

Merge branch 'akpm' (patches from Andrew)

2021-11-06T21:08:17+00:00

Merge misc updates from Andrew Morton:
 "257 patches.

  Subsystems affected by this patch series: scripts, ocfs2, vfs, and
  mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
  gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
  pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
  memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
  vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
  cleanups, kfence, and damon)"

* emailed patches from Andrew Morton : (257 commits)
  mm/damon: remove return value from before_terminate callback
  mm/damon: fix a few spelling mistakes in comments and a pr_debug message
  mm/damon: simplify stop mechanism
  Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
  Docs/admin-guide/mm/damon/start: simplify the content
  Docs/admin-guide/mm/damon/start: fix a wrong link
  Docs/admin-guide/mm/damon/start: fix wrong example commands
  mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
  mm/damon: remove unnecessary variable initialization
  Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
  mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
  selftests/damon: support watermarks
  mm/damon/dbgfs: support watermarks
  mm/damon/schemes: activate schemes based on a watermarks mechanism
  tools/selftests/damon: update for regions prioritization of schemes
  mm/damon/dbgfs: support prioritization weights
  mm/damon/vaddr,paddr: support pageout prioritization
  mm/damon/schemes: prioritize regions within the quotas
  mm/damon/selftests: support schemes quotas
  mm/damon/dbgfs: support quotas of schemes
  ...

memblock: use memblock_free for freeing virtual pointers

2021-11-06T20:30:41+00:00

Rename memblock_free_ptr() to memblock_free() and use memblock_free()
when freeing a virtual pointer so that memblock_free() will be a
counterpart of memblock_alloc()

The callers are updated with the below semantic patch and manual
addition of (void *) casting to pointers that are represented by
unsigned long variables.

    @@
    identifier vaddr;
    expression size;
    @@
    (
    - memblock_phys_free(__pa(vaddr), size);
    + memblock_free(vaddr, size);
    |
    - memblock_free_ptr(vaddr, size);
    + memblock_free(vaddr, size);
    )

[sfr@canb.auug.org.au: fixup]
  Link: https://lkml.kernel.org/r/20211018192940.3d1d532f@canb.auug.org.au

Link: https://lkml.kernel.org/r/20210930185031.18648-7-rppt@kernel.org
Signed-off-by: Mike Rapoport 
Signed-off-by: Stephen Rothwell 
Cc: Christophe Leroy 
Cc: Juergen Gross 
Cc: Shahab Vahedi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds