Address Sanitizer detected the following when running serviceability/dcmd/framework/VMVersionTest.java:

 6339 ==3480302==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f7952e18480 at pc 0x7f795d0a141d bp 0x7f7952e18210 sp 0x7f7952e179b8
 6340 READ of size 23 at 0x7f7952e18480 thread T1
 6341 #0 0x7f795d0a141c (/lib/x86_64-linux-gnu/libasan.so.5+0x4f41c)
 6342 #1 0x7f7957687d3f in get_user_name_slow /home/jb/work/jbr-dev/src/hotspot/os/posix/perfMemory_posix.cpp:550
 6343 #2 0x7f795768cb31 in get_user_name_slow /home/jb/work/jbr-dev/src/hotspot/share/memory/resourceArea.hpp:99
 6344 #3 0x7f795768cb31 in get_user_name /home/jb/work/jbr-dev/src/hotspot/os/posix/perfMemory_posix.cpp:661
 6345 #4 0x7f795768cb31 in mmap_attach_shared /home/jb/work/jbr-dev/src/hotspot/os/posix/perfMemory_posix.cpp:1133
 6346 #5 0x7f795766c983 in Perf_Attach /home/jb/work/jbr-dev/src/hotspot/share/prims/perf.cpp:89
 6347 #6 0x7f793b111ba7 (<unknown module>)
 6348
 6349 Address 0x7f7952e18480 is located in stack of thread T1 at offset 496 in frame
 6350 #0 0x7f7957687b8f in get_user_name_slow /home/jb/work/jbr-dev/src/hotspot/os/posix/perfMemory_posix.cpp:514
 6351
 6352 This frame has 4 object(s):
 6353 [48, 56) 'remainder' (line 191)
 6354 [80, 224) 'statbuf' (line 603)
 6355 [288, 432) 'statbuf' (line 248)
 6356 [496, 4593) 'buffer' (line 540) <== Memory access at offset 496 is inside this variable


The bug is in get_user_name_slow()(src/hotspot/os/posix/perfMemory_posix.cpp): on Linux, the 'buffer' array may be used after going out of scope.