Comment 0 for bug 1843018

Using kernel 5.0.0-27-generic on Ubuntu 18.04 in a container, every pathname in /proc/<pid>/maps is / instead of the mapped file path.

This appears to be a regression in 5.0.0-27-generic; it works on 5.0.0-25-generic. The problem can be reproduced in various Ubuntu releases, e.g. 18.04 and 19.04.

5.0.0-25-generic (working):

$ sudo docker run ubuntu cat /proc/1/maps
56324a3f5000-56324a3fd000 r-xp 00000000 fc:01 665673 /bin/cat
56324a5fc000-56324a5fd000 r--p 00007000 fc:01 665673 /bin/cat
56324a5fd000-56324a5fe000 rw-p 00008000 fc:01 665673 /bin/cat
56324a8eb000-56324a90c000 rw-p 00000000 00:00 0 [heap]
7f8ab5f91000-7f8ab6178000 r-xp 00000000 fc:01 666073 /lib/x86_64-linux-gnu/libc-2.27.so
7f8ab6178000-7f8ab6378000 ---p 001e7000 fc:01 666073 /lib/x86_64-linux-gnu/libc-2.27.so
7f8ab6378000-7f8ab637c000 r--p 001e7000 fc:01 666073 /lib/x86_64-linux-gnu/libc-2.27.so
7f8ab637c000-7f8ab637e000 rw-p 001eb000 fc:01 666073 /lib/x86_64-linux-gnu/libc-2.27.so
7f8ab637e000-7f8ab6382000 rw-p 00000000 00:00 0
7f8ab6382000-7f8ab63a9000 r-xp 00000000 fc:01 666055 /lib/x86_64-linux-gnu/ld-2.27.so
7f8ab6583000-7f8ab65a7000 rw-p 00000000 00:00 0
7f8ab65a9000-7f8ab65aa000 r--p 00027000 fc:01 666055 /lib/x86_64-linux-gnu/ld-2.27.so
7f8ab65aa000-7f8ab65ab000 rw-p 00028000 fc:01 666055 /lib/x86_64-linux-gnu/ld-2.27.so
7f8ab65ab000-7f8ab65ac000 rw-p 00000000 00:00 0
7ffc25954000-7ffc25975000 rw-p 00000000 00:00 0 [stack]
7ffc259f1000-7ffc259f4000 r--p 00000000 00:00 0 [vvar]
7ffc259f4000-7ffc259f5000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
5.0.0-27-generic (broken):

$ sudo docker run ubuntu cat /proc/1/maps
55de0e052000-55de0e05a000 r-xp 00000000 fc:01 665673 /
55de0e259000-55de0e25a000 r--p 00007000 fc:01 665673 /
55de0e25a000-55de0e25b000 rw-p 00008000 fc:01 665673 /
55de0fcb3000-55de0fcd4000 rw-p 00000000 00:00 0 [heap]
7f7a8d881000-7f7a8da68000 r-xp 00000000 fc:01 666073 /
7f7a8da68000-7f7a8dc68000 ---p 001e7000 fc:01 666073 /
7f7a8dc68000-7f7a8dc6c000 r--p 001e7000 fc:01 666073 /
7f7a8dc6c000-7f7a8dc6e000 rw-p 001eb000 fc:01 666073 /
7f7a8dc6e000-7f7a8dc72000 rw-p 00000000 00:00 0
7f7a8dc72000-7f7a8dc99000 r-xp 00000000 fc:01 666055 /
7f7a8de73000-7f7a8de97000 rw-p 00000000 00:00 0
7f7a8de99000-7f7a8de9a000 r--p 00027000 fc:01 666055 /
7f7a8de9a000-7f7a8de9b000 rw-p 00028000 fc:01 666055 /
7f7a8de9b000-7f7a8de9c000 rw-p 00000000 00:00 0
7ffc744bd000-7ffc744de000 rw-p 00000000 00:00 0 [stack]
7ffc7452d000-7ffc74530000 r--p 00000000 00:00 0 [vvar]
7ffc74530000-7ffc74531000 r-xp 00000000 00:00 0 [vdso]