{bp-19198} mm,qemu: Fix KASAN user-space false positives, global region link error, and linker script section placement#19273
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…_KERNEL on When CONFIG_MM_KASAN_GLOBAL is enabled, hook.c is also linked into libmm.a. However, g_global_region (defined in global.c) is only injected into the nuttx ELF by kasan_global.py — it does not process the app binary. This causes undefined symbol errors when linking an app against libmm.a. Guard the inclusion of global.c with __KERNEL__ so that only kernel builds pull in the global KASAN region, while app builds fall back to the no-op stub. Signed-off-by: leisiji <2265215145@qq.com>
When CONFIG_BUILD_KERNEL is enabled, user-space and kernel-space have separate address spaces. User-space addresses passed via syscalls (e.g., open) are registered by KASAN but should not be monitored, as they are not kernel heap allocations. This causes KASAN to report false positives on user-space pointers accessed through system calls. Mark the user-space heap with nokasan=true so KASAN skips checking its address range, consistent with how rptun already handles this. Signed-off-by: leisiji <2265215145@qq.com>
1. The .kasan.unused and .kasan.global sections contain compiler-generated data with the WRITE flag (.data..LASAN*), but the linker script placed them before .text without specifying a memory region. The linker could not put writable sections into the read-only ROM (rx) region, so it silently placed them at 0x40000000 in RAM, creating an extra LOAD segment that conflicts with QEMU virt's RAM layout and causes boot failure. 2. The .kasan.global should be placed before .data because .data patten (*(.data*)) includes .kasan.global pattern (*(.data..LASAN0)), and it cause kasan_global.py cannot find .kasan.global section to generate the g_global_region array. 3. Move .kasan.shadows from before .text to after .rodata. Placing it before .text causes .text to shift when .kasan.shadows transitions from empty (pass 1) to populated (pass 2+), preventing the multi-pass link addresses from converging. After .rodata it does not affect any upstream section addresses. 4. Add CMake post-build step to strip .kasan.unused and .kasan.global sections from the final binary, matching the Makefile build behavior. Signed-off-by: leisiji <2265215145@qq.com>
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Summary
When CONFIG_MM_KASAN and CONFIG_BUILD_KERNEL are both enabled on
qemu-armv7a:knsh, there are three issues preventing correct build
and runtime: (1) user-space heap false positive KASAN reports,
(2) app link failure due to undefined g_global_region symbol,
(3) linker script misplaces KASAN sections causing boot failure.
This series fixes all three issues to make KASAN work correctly
in kernel mode on QEMU ARMv7-A.
Impact
RELEASE
Testing
CI