[PATCH v14 01/92] dyndbg: fix NULL ptr on i386 due to section mis-alignment

Jim Cromie
2026-04-23T20:54:08Z

When dyndbg classmaps get used (later in this series), the
__dyndbg_classes section (which has 28 byte structs on i386), causes
mis-alignment of the following __dyndbg section, resulting in a NULL
pointer deref in dynamic_debug_init().

Fix this by:

Adding ALIGN(8) to the BOUNDED_SECTION* macros. This aligns all
sections using those macros, including the problem section above.
Almost all the other macro uses are already ALIGN(8), either
directly or by being below one.

Removing BOUNDED_SECTION* uses in ORC_UNWINDER sections. These
explicitly have smaller alignments, and using the modified macros here
would override that alignment, which scripts/sorttable.c does not
tolerate.

Move __dyndbg section back above __dyndbg_classes, restoring its
original position. This is cosmetic, given the alignment added to the
macros.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202601211325.7e1f336-lkp@intel.com
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/asm-generic/vmlinux.lds.h | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 60c8c22fd3e4..db38f52035f3 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -212,11 +212,13 @@
#endif

#define BOUNDED_SECTION_PRE_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ . = ALIGN(8); \
_BEGIN_##_label_ = .; \
KEEP(*(_sec_)) \
_END_##_label_ = .;

#define BOUNDED_SECTION_POST_LABEL(_sec_, _label_, _BEGIN_, _END_) \
+ . = ALIGN(8); \
_label_##_BEGIN_ = .; \
KEEP(*(_sec_)) \
_label_##_END_ = .;
@@ -862,15 +864,21 @@
#ifdef CONFIG_UNWINDER_ORC
#define ORC_UNWIND_TABLE \
.orc_header : AT(ADDR(.orc_header) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_header, _orc_header) \
+ __start_orc_header = .; \
+ KEEP(*(.orc_header)) \
+ __stop_orc_header = .; \
} \
. = ALIGN(4); \
.orc_unwind_ip : AT(ADDR(.orc_unwind_ip) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_unwind_ip, _orc_unwind_ip) \
+ __start_orc_unwind_ip = .; \
+ KEEP(*(.orc_unwind_ip)) \
+ __stop_orc_unwind_ip = .; \
} \
. = ALIGN(2); \
.orc_unwind : AT(ADDR(.orc_unwind) - LOAD_OFFSET) { \
- BOUNDED_SECTION_BY(.orc_unwind, _orc_unwind) \
+ __start_orc_unwind = .; \
+ KEEP(*(.orc_unwind)) \
+ __stop_orc_unwind = .; \
} \
text_size = _etext - _stext; \
. = ALIGN(4); \

--
2.53.0