Critical Regression: smbfs 7.0 introduces a crtitical bug regarding symlinks

App & System Services Core OS
mfh OP
Created
Replies 4
Boosts 5
Views 314
Participants 4

Apple feedback FB25355124

The SMB client no longer accepts reads to symlinks that are an absolute path to a network volume or a symlink that contains a (..) in the relative path.

Reproduction steps on an SMB mount with this file structure:

  • dir
    • a.txt

  1. Run this command from inside of "dir":

    ln -s my-link ../dir/a.txt

  2. Attempt to read that symlink:

    cat ./my-link

    Which results in this error:
    cat: link: Invalid argument

    which is translating to an EINVAL getting returned from the SMB client.

  3. Same behavior was observed when making a symlink with an absolute path:

    ln -s my-link /Volumes/Example/dir/a.txt

The server is responding successfully to the IOCTL command but the client is still rejecting the request with that error.

This behavior was not observed in macOS 26.6.2 (smbfs 6.0.1) as well as previous versions of macOS.

Answered by DTS Engineer in 915381022
Written by mfh in 854029021

Apple feedback FB25355124

Written by SNDWD in 914393022

I have also submitted a separate bug report: FB25362340.

Written by JMP Humphrey in 915126022

I have also submitted a bug report: FB25465081.

Thanks folks.

Just so we’re on the same page:

  • Apple Developer Forums is primary focusing on helping folks with Apple APIs and developer tools. This issue is not that, as witnessed by the fact that mfh’s steps to reproduce only involved command-line tools.
  • We generally redirect such questions to Apple Support Community, run by Apple Support.
  • But for straight up bug reports like this, the best path forward is Feedback Assistant.
  • I don’t have any concrete info to share as to when this will be fixed but, as always, I encourage you to re-test with new beta releases as we seed them.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Replies  4
Boosts 5
Views  314
Participants  4
SNDWD OP

I can confirm the same issue on macOS 27.2 and macOS 27.3 Beta 1.

In my case, the SMB server is running TrueNAS CORE 13, and the affected files are Minshall+French (XSym) symbolic links.

I was able to reproduce the issue consistently:

  • Relative symlinks without .. work correctly.
  • Relative symlinks containing .. are incorrectly interpreted as regular 1067-byte files.
  • Long relative target paths without .. work correctly.
  • The same symlinks work correctly on macOS 14.8.8 when accessing the identical SMB share.

Disabling SMB metadata caching (nomdatacache), switching to SMB 2.1, and disabling SMB streams did not resolve the issue.

This regression is affecting production workflows involving linked media files.

I have also submitted a separate bug report: FB25362340.
JMP Humphrey OP

We are seeing the same. Worked fine until 26.7.2 and 27.2.

We verified older versions are still able to access the builds via the links. It also seems to impact copying in finder or terminal if the bundle contains symlinks (as in a Mac build).

It all works with 14.8.9 (smbfs 5.1).

I have also submitted a bug report: FB25465081.

DTS Engineer OP
Apple
Recommended
Written by mfh in 854029021

Apple feedback FB25355124

Written by SNDWD in 914393022

I have also submitted a separate bug report: FB25362340.

Written by JMP Humphrey in 915126022

I have also submitted a bug report: FB25465081.

Thanks folks.

Just so we’re on the same page:

  • Apple Developer Forums is primary focusing on helping folks with Apple APIs and developer tools. This issue is not that, as witnessed by the fact that mfh’s steps to reproduce only involved command-line tools.
  • We generally redirect such questions to Apple Support Community, run by Apple Support.
  • But for straight up bug reports like this, the best path forward is Feedback Assistant.
  • I don’t have any concrete info to share as to when this will be fixed but, as always, I encourage you to re-test with new beta releases as we seed them.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
SNDWD OP

Thank you!

I can confirm that the SMB symlink regression appears to be fixed in macOS 27.2.1 (Build 26B131).

I successfully tested both existing and newly created Minshall+French (XSym) symlinks containing .. in their relative target paths. Previously affected symlinks are now recognized correctly, and their target files can be accessed again.

The issue is still present in macOS 27.3 Beta 1 on a separate Mac, so hopefully the fix will be included in the next beta release.

I have also updated my Apple Feedback report FB25362340 with these results.