RFR: 8350201: Out of bounds access on Linux aarch64 in os::print_register_info

[David Holmes]

On Mon, 17 Feb 2025 15:16:22 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> When running jtreg test VendorInfoPluginsTest we noticed the following issue (ubsanized binaries were used)
> 
> 
> jdk/src/hotspot/os_cpu/linux_aarch64/os_linux_aarch64.cpp:369:46: runtime error: index 31 out of bounds for type 'long long unsigned int [31]'
>     #0 0xffff84380470 in os::print_register_info(outputStream*, void const*, int&) (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x4d80470)
>     #1 0xffff84bf566c in VMError::report(outputStream*, bool) (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x55f566c)
>     #2 0xffff84bf812c in VMError::report_and_die(int, char const*, char const*, std::__va_list, Thread*, unsigned char*, void const*, void const*, char const*, int, unsigned long) (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x55f812c)
>     #3 0xffff84bf90b4 in VMError::report_and_die(Thread*, unsigned int, unsigned char*, void const*, void const*, char const*, ...) (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x55f90b4)
>     #4 0xffff84bf9138 in VMError::report_and_die(Thread*, unsigned int, unsigned char*, void const*, void const*) (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x55f9138)
>     #5 0xffff8489ede8 in JVM_handle_linux_signal (/jtreg_jdk_tier2_work/JTwork/scratch/10/images/vendorinfo.image/lib/server/libjvm.so+0x529ede8)
> 
> 
> Looks like we have registers 0 - 30 according to sys/ucontext.h on Linux aarch64
> 
> 
> typedef struct
>   {
>     unsigned long long int __ctx(fault_address);
>     unsigned long long int __ctx(regs)[31];
>     ....
>   } mcontext_t;
> 
> 
> and according to the arm developer documentation
> 
> https://developer.arm.com/documentation/100069/0606/Overview-of-AArch64-state/Registers-in-AArch64-state#:~:text=In%20AArch64%20state%2C%20the%20following,are%20accessible%20as%20W0%2DW30.
> 
> "Thirty-one 64-bit general-purpose registers X0-X30, the bottom halves of which are accessible as W0-W30."

Looks good. I've updated the bug report with the history. Interesting BSD and Windows use completely different register sets on Aarch64 compared to linux.

Thanks

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Marked as reviewed by dholmes (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23667#pullrequestreview-2622433259