xbc_snprint_cmdline() is meant to be called twice: first with
buf=NULL, size=0 to probe the rendered length, then with a real
buffer to fill it (the standard snprintf() two-pass pattern). The
probe call makes the function compute "buf + size" (NULL + 0) and,
on every iteration, advance "buf += ret" from that NULL base and
pass the result back into snprintf().
Pointer arithmetic on a NULL pointer is undefined behavior. It is
harmless in the in-kernel callers today, but the follow-up patches
run this same code in the userspace tools/bootconfig parser at kernel
build time, where host UBSan / FORTIFY_SOURCE abort the build.
Track a running written length (size_t) instead of mutating @buf, and
only form "buf + len" when @buf is non-NULL. snprintf(NULL, 0, ...)
is itself well defined and returns the would-be length, so the
two-pass "probe then fill" usage returns identical byte counts.
Link: https://lore.kernel.org/all/20260626-bootconfig_using_tools-v7-1-24ab72139c29@debian.org/
Fixes: 51887d03ac ("bootconfig: init: Allow admin to use bootconfig for kernel command line")
Cc: stable@vger.kernel.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Move xbc_snprint_cmdline() from init/main.c to lib/bootconfig.c so the
function (and its xbc_namebuf scratch buffer) becomes part of the shared
parser library. tools/bootconfig already compiles lib/bootconfig.c
directly, which lets a follow-up patch reuse the same renderer in the
userspace tool to convert a bootconfig file into a flat cmdline string
at build time.
No functional change.
Link: https://lore.kernel.org/all/20260508-bootconfig_using_tools-v1-1-1132219aa773@debian.org/
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Pull memblock updates from Mike Rapoport:
- improve debuggability of reserve_mem kernel parameter handling with
print outs in case of a failure and debugfs info showing what was
actually reserved
- Make memblock_free_late() and free_reserved_area() use the same core
logic for freeing the memory to buddy and ensure it takes care of
updating memblock arrays when ARCH_KEEP_MEMBLOCK is enabled.
* tag 'memblock-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
x86/alternative: delay freeing of smp_locks section
memblock: warn when freeing reserved memory before memory map is initialized
memblock, treewide: make memblock_free() handle late freeing
memblock: make free_reserved_area() update memblock if ARCH_KEEP_MEMBLOCK=y
memblock: extract page freeing from free_reserved_area() into a helper
memblock: make free_reserved_area() more robust
mm: move free_reserved_area() to mm/memblock.c
powerpc: opal-core: pair alloc_pages_exact() with free_pages_exact()
powerpc: fadump: pair alloc_pages_exact() with free_pages_exact()
memblock: reserve_mem: fix end caclulation in reserve_mem_release_by_name()
memblock: move reserve_bootmem_range() to memblock.c and make it static
memblock: Add reserve_mem debugfs info
memblock: Print out errors on reserve_mem parser
It shouldn't be responsibility of memblock users to detect if they free
memory allocated from memblock late and should use memblock_free_late().
Make memblock_free() and memblock_phys_free() take care of late memory
freeing and drop memblock_free_late().
Link: https://patch.msgid.link/20260323074836.3653702-9-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
lib/bootconfig.c:136:21: warning: conversion from 'long int' to
'int' may change value [-Wconversion]
lib/bootconfig.c:308:33: warning: conversion from 'int' to 'uint16_t'
may change value [-Wconversion]
lib/bootconfig.c:467:37: warning: conversion from 'int' to 'uint16_t'
may change value [-Wconversion]
lib/bootconfig.c:469:40: warning: conversion from 'int' to 'uint16_t'
may change value [-Wconversion]
lib/bootconfig.c:472:54: warning: conversion from 'int' to 'uint16_t'
may change value [-Wconversion]
lib/bootconfig.c:476:45: warning: conversion from 'int' to 'uint16_t'
may change value [-Wconversion]
xbc_node_index() returns the position of a node in the xbc_nodes array,
which has at most XBC_NODE_MAX (8192) entries, well within uint16_t
range. Every caller stores the result in a uint16_t field (node->parent,
node->child, node->next, or the keys[] array in compose_key_after), so
the int return type causes narrowing warnings at all six call sites.
Change the return type to uint16_t and add an explicit cast on the
pointer subtraction to match the storage width and eliminate the
warnings.
Link: https://lore.kernel.org/all/20260318155919.78168-14-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
lib/bootconfig.c:839:24: warning: conversion from 'size_t' to 'int'
may change value [-Wconversion]
lib/bootconfig.c:860:32: warning: conversion from 'size_t' to 'int'
may change value [-Wconversion]
lib/bootconfig.c:860:29: warning: conversion to 'size_t' from 'int'
may change the sign of the result [-Wsign-conversion]
The key length variables len and wlen accumulate strlen() results but
were declared as int, causing truncation and sign-conversion warnings.
Change both to size_t to match the strlen() return type and avoid
mixed-sign arithmetic.
Link: https://lore.kernel.org/all/20260318155919.78168-13-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
lib/bootconfig.c:415:32: warning: conversion to 'long unsigned int'
from 'long int' may change the sign of the result [-Wsign-conversion]
Pointer subtraction yields ptrdiff_t (signed), which was stored in
unsigned long. The original unsigned type implicitly caught a negative
offset (data < xbc_data) because the wrapped value would exceed
XBC_DATA_MAX. Make this intent explicit by using a signed long and
adding an offset < 0 check to the WARN_ON condition.
Link: https://lore.kernel.org/all/20260318155919.78168-12-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
lib/bootconfig.c:198:19: warning: conversion from 'size_t' to 'int'
may change value [-Wconversion]
lib/bootconfig.c:200:33: warning: conversion to '__kernel_size_t'
from 'int' may change the sign of the result [-Wsign-conversion]
strlen() returns size_t but the result was stored in an int. The value
is then passed back to strncmp() which expects size_t, causing a second
sign-conversion warning on the round-trip. Use size_t throughout to
match the API types.
Link: https://lore.kernel.org/all/20260318155919.78168-11-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
xbc_verify_tree() validates that each node's next index is within
bounds, but does not check the child index. Add the same bounds
check for the child field.
Without this check, a corrupt bootconfig that passes next-index
validation could still trigger an out-of-bounds memory access via an
invalid child index when xbc_node_get_child() is called during tree
traversal at boot time.
Link: https://lore.kernel.org/all/20260318155919.78168-9-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Move the xbc_node_num increment to after xbc_init_node() so a failed
init does not leave a partially initialized node counted in the array.
If xbc_init_node() fails on a data offset at the boundary of a
maximum-size bootconfig, the pre-incremented count causes subsequent
tree verification and traversal to consider the uninitialized node as
valid, potentially leading to an out-of-bounds read or unpredictable
boot behavior.
Link: https://lore.kernel.org/all/20260318155919.78168-5-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Valid node indices are 0 to xbc_node_num-1, so a next value equal to
xbc_node_num is out of bounds. Use >= instead of > to catch this.
A malformed or corrupt bootconfig could pass tree verification with
an out-of-bounds next index. On subsequent tree traversal at boot
time, xbc_node_get_next() would return a pointer past the allocated
xbc_nodes array, causing an out-of-bounds read of kernel memory.
Link: https://lore.kernel.org/all/20260318155919.78168-4-objecting@objecting.org/
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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: e5efaeb8a8 ("bootconfig: Support mixing a value and subkeys under a key")
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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: 76db5a27a8 ("bootconfig: Add Extra Boot Config support")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
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: ead1e19ad9 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law <objecting@objecting.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
__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: ead1e19ad9 ("lib/bootconfig: Fix a bug of breaking existing tree nodes")
Cc: stable@vger.kernel.org
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Terminate the value search for a key if it hits a newline and make
the value empty.
When we pass a bootconfig with an empty value terminated by the
newline, like below::
foo =
bar = value
Current bootconfig interprets it as a single entry::
foo = "bar = value";
The Documentation/admin-guide/bootconfig.rst defines the value
itself is terminated by newline:
The value has to be terminated by semi-colon (``;``) or newline (``\n``).
but it does not define when the value search is terminated.
This changes the behavior to be more line-oriented, so that it is
clearer in how it works.
- The value search of key-value pair will be terminated by a comment
or newline.
- The value search of an array will continue beyond comments and
newlines.
Thus, with this update, the above example is interpreted as::
foo = "";
bar = "value";
And the below example will cause a syntax error because "bar" is expected
as a key but it has ','.
foo =
bar, buz
According to this change, one wrong example config is updated.
Link: https://lore.kernel.org/all/177025238503.14982.17059549076175612447.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
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 <thorsten.blum@toblux.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
