[CRIU] ACK: [PATCH v3][SRU][H] UBUNTU: SAUCE: overlayfs: fix incorrect mnt_id of files opened from map_files

[Krzysztof Kozlowski]

On 07/05/2021 08:11, Seth Forshee wrote:
> From: Alexander Mikhalitsyn <alexander at mihalicyn.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1857257
> 
> The hack was introduced in ("UBUNTU: SAUCE: overlayfs: allow with
> shiftfs as underlay") and it broke checkpoint/restore of docker
> contains:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1857257
> 
> The following script can be used to trigger the issue:
>   #!/bin/bash
> 
>   cat > test.py << EOF
>   import sys
> 
>   f = open("/proc/self/maps")
> 
>   for l in f.readlines():
>     if "python" not in l:
>       continue
>     print(l)
>     s = l.split()
>     start, end = s[0].split("-")
>     fname = s[-1]
>     print(start, end, fname)
>     break
>   else:
>     sys.exit(1)
> 
>   test_file1 = open(fname)
>   test_file2 = open("/proc/self/map_files/%s-%s" % (start, end))
> 
>   fdinfo1 = open("/proc/self/fdinfo/%d" % test_file1.fileno()).read()
>   fdinfo2 = open("/proc/self/fdinfo/%d" % test_file2.fileno()).read()
> 
>   if fdinfo1 != fdinfo2:
>     print("FAIL")
>     print(test_file1)
>     print(fdinfo1)
>     print(test_file2)
>     print(fdinfo2)
>     sys.exit(1)
>   print("PASS")
>   EOF
>   sudo docker run -it --privileged --rm -v `pwd`:/mnt python python /mnt/test.py
> 
> Thanks to Andrei Vagin for the reproducer and investigation of this problem.
> 
> Cc: Andrei Vagin <avagin at gmail.com>
> Cc: Adrian Reber <areber at redhat.com>
> Cc: Christian Brauner <christian.brauner at ubuntu.com>
> Cc: Stefan Bader <stefan.bader at canonical.com>
> Cc: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
> Cc: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>
> 
> Fixes: d24b8a5 ("UBUNTU: SAUCE: overlayfs: allow with shiftfs as underlay")
> Signed-off-by: Alexander Mikhalitsyn <alexander at mihalicyn.com>
> [ saf: resolve conflicts with "ovl: fix reference counting in ovl_mmap
>   error path" ]
> Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
> ---
> 
> Update for hirsute only to resolve conflicts with recent stable updates.
> Tested in the same way as before.
> 
>  fs/overlayfs/file.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> 


Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski at canonical.com>


Best regards,
Krzysztof