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Something very weird I came across, any thoughts would be much appreciated:

Some software (httrack) created a directory structure. Using my user (which also ran the software), I cannot view the directory:

ls -ltra feed/
ls: cannot access 'feed/.': Permission denied
ls: cannot access 'feed/..': Permission denied
ls: cannot access 'feed/atom': Permission denied
total 0
-????????? ? ? ? ?            ? atom
d????????? ? ? ? ?            ? ..
d????????? ? ? ? ?            ? .

As root I can list the contents just fine:

ls -ltra feed/
total 68
-rw-r--r-- 1 ys ys 59100 Oct 22 13:30 atom
drw-r--r-- 2 ys ys  4096 Oct 22 22:51 .
drwxr-xr-x 8 ys ys  4096 Oct 23 00:00 ..

But it gets more weird: as user nobody, I get the same results as root (!).

The OS is a Linux Mint (Debian derived) version ulyana running Linux 5.4.0-40, the filesystem is ext4 (with discard) on a crypt LVM on an SSD in an Intel laptop (lenovo x1 carbon, gen4). The ram is non-ECC.

Is there a logical explanation? I'll start by running memtest...

Joris
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    Add the execute bits back to your feed directory to fix this (chmod a+x feed). No idea why it works for nobody, it shouldn't. Everything else is behaving exactly as I would expect for a directory with read but no execute permissions. –  Oct 23 '20 at 09:24
  • Thanks for your reply, but the problem wasn't filesystem permissions. – Joris Oct 27 '20 at 07:11

1 Answers1

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So, after a reboot the system was in perfect order. I ran memtest86+, badblocks and cpuburn. No errors were found anywhere and the smart self asesment was clean. Verifying the integrity of the (bulk of the) filesystem contents from the most recent backup yielded nothing, but that certainly isn't exhaustive obviously.

Honestly I have no idea what happened, so I'm going to chalk it up to "transient corruption". The machine has been destroyed to avoid the accident/temptation of using it again.

If you read this because you find yourself in the same situation (xkcd 979) I wish you good luck.

Joris
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