Bug report

A python file read crashes weirdly with raw readinto() returned invalid length 4494852078 (should have been between 0 and 2297167872).

See there:

borgbackup/borg#6140 (comment)

That "returned invalid length" is even more than the total file length.

It is currently rather unclear what the root cause of this is, this is why I am asking for help / clarification here.

Considering it crashes at a sanity check within the python stdlib, I suspect the bug is either somewhere deeper in CPython or in some lower layer (like fs or os / kernel / hardware level).

Your environment

• CPython versions tested on: 3.7
• Operating system and architecture: Linux 64bit / ZFS (Hetzner Storage Box, Server hw with ECC memory)

Note:

I of course already tried to find more information about this kind of error doing a web search. But all I found are cases of:

• network reads (but in our cases we have a normal fs read and the fs is locally attached to the storage box as Hetzner told us)
• terminal / text encoding / crlf related stuff, also does not match our case

I guess this is the place that raises this exception:

• https://github.com/python/cpython/blob/v3.7.1/Modules/_io/bufferedio.c#L1493
• https://github.com/python/cpython/blob/v3.10.4/Modules/_io/bufferedio.c#L1499