Junbo-Zheng opened a new pull request, #19486:
URL: https://github.com/apache/nuttx/pull/19486
## Summary
A crash was observed when running `ps`: a BusFault in nxtask_argvstr
dereferencing tl_argv, because a thread's stack overflow had silently
corrupted the TLS region where tl_argv resides.
On ARMv8-M with CONFIG_ARMV8M_STACKCHECK_HARDWARE, PSPLIM was set to
stack_alloc_ptr -- the bottom of the stack allocation where TLS begins.
The stack grows downward, and TLS occupies [stack_alloc_ptr,
stack_alloc_ptr + tls_info_size()), so an overflow crossed into TLS and
clobbered tl_argv before SP ever reached the limit. The overflow went
undetected and only surfaced later as an unrelated BusFault in code
that read the corrupted TLS data (such as ps iterating the task list).
Set the limit to stack_alloc_ptr + tls_info_size() -- the top of the
TLS region and the usable stack base -- so an overflow faults at the
TLS boundary, before any TLS byte is touched. Include <tls/tls.h> for
the tls_info_size() macro, which is the value sched reserves for the
TLS region via up_stack_frame().
## Impact
Behavior change only for overflowing threads -- a thread
that previously overflowed silently into TLS now triggers an immediate
Stack Overflow fault at the offending function. Well-behaved threads
are unaffected; usable stack size is unchanged (TLS already occupied
those bytes).
## Testing
Built on the upstream nuttx tree (Ubuntu, arm-none-eabi-gcc 13.2.1) for
stm32l562e-dk:nsh (Cortex-M33, ARMv8-M). The change is under
#ifdef CONFIG_ARMV8M_STACKCHECK_HARDWARE, which is off by default, so it
must be enabled to exercise the code:
```bash
$ make distclean
$ tools/configure.sh -l stm32l562e-dk:nsh
$ sed -i 's|^# CONFIG_ARMV8M_STACKCHECK_HARDWARE is not
set|CONFIG_ARMV8M_STACKCHECK_HARDWARE=y|' .config
$ make olddefconfig
$ make -j20
LD: nuttx
Memory region Used Size Region Size %age Used
flash: 190832 B 1015 KB 18.36%
sram: 9704 B 192 KB 4.94%
CP: nuttx.bin
$ ls -la nuttx nuttx.bin
-rwxrwxr-x 1 mi mi 2124048 Jul 20 17:37 nuttx
-rwxrwxr-x 1 mi mi 190832 Jul 20 17:37 nuttx.bin
```
This makes a stack overflow fault at its source, so on hardware the
offending task is surfaced immediately and the root cause (insufficient
stack) is fixed by enlarging the stack -- caught proactively, rather
than only appearing later as a delayed BusFault in ps when it reads the
corrupted TLS.
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