[Bug 2130973] Re: Sudo-rs panics executing shell script without execute permission

[Ghadi Rahme]

Questing verification:


Installed sudo-rs package is from proposed:

root at build-questing:~/test# apt list --installed sudo-rs
sudo-rs/questing-proposed,now 0.2.8-1ubuntu5.3 amd64 [installed,automatic]
Notice: There are 2 additional versions. Please use the '-a' switch to see them.


1. Create file
root at build-questing:~/test# touch test.sh

2. Make sure it does not have exec permissions
root at build-questing:~/test# ls -l test.sh 
-rw-r--r-- 1 root root 0 Jan 20 17:06 test.sh

3. Run sudo on the file
root at build-questing:~/test# sudo ./test.sh 
sudo-rs: cannot execute '/root/test/test.sh': Permission denied (os error 13)

sudo returns permission denied without showing any stack trace.

** Tags removed: verification-needed-questing
** Tags added: verification-done-questing

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https://bugs.launchpad.net/bugs/2130973

Title:
  Sudo-rs panics executing shell script without execute permission

Status in rust-sudo-rs package in Ubuntu:
  Fix Released
Status in rust-sudo-rs source package in Questing:
  Fix Committed

Bug description:
  Thank you @platform34 for the original description!

  [Impact]
  Currently running sudo-rs on a script with no execute permissions will lead to a crash of the program. This harms scripts which might expect only a permission denied error and handle them gracefully if they arise. The fix has been made available upstream here: https://github.com/trifectatechfoundation/sudo-rs/commit/eeb1ad77237353cbdf53772ca5278cd1dd1aed1b

  Ubuntu 26.04 already has the fix but 25.10 is affected.

  [Test Plan]
  1. Create a new file and make sure it has no execute permissions:
  $ touch test.sh
  $ ls -l test.sh
  -rw-rw-r-- 1 ghadi ghadi 0 Jan  9 18:41 test.sh

  2. Run sudo on the file while using sudo-rs and the following error
  will be shown:

  $ sudo ./test.sh                                    
  [sudo: authenticate] Password: 

  thread 'main' panicked at src/exec/use_pty/monitor.rs:283:45:
  internal error: entered unreachable code
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
  sudo-rs: cannot execute '/path/to/test.sh': Permission denied (os error 13)

  
  The expected behavior is the following output:
  $ sudo ./test.sh 
  sudo-rs: cannot execute '/path/to/test.sh': Permission denied (os error 13)

  Where only the permission denied error is printed and sudo does not
  panic.

  
  [ Where problems could occur ]

  * Since the changes touch on how error messages are sent in sudo-rs,
  it is possible that it might block some errors from properly
  propagating.

  
  [original description]
  My Ubuntu Budgie install was updated to Ubuntu 25.10 last week which replaced sudo with the rust sudo-rs version 0.2.8.

  Today I was executing a bash script with sudo and forgot to grant the
  script execute permission. Not a big problem however the response from
  sudo-rs was a panic, rather than a gracefully handled error message.

  I retested with a very simple script and the panic is 100%
  reproducible.

  Is this the same bug as:
  https://github.com/trifectatechfoundation/sudo-rs/pull/1298

  sudo ./test

  #!/bin/bash
  sudo apt update

  thread ‘main’ panicked at src/exec/use_pty/monitor.rs:283:45:
  internal error: entered unreachable code
  note: run with RUST_BACKTRACE=1 environment variable to display a backtrace
  sudo-rs: cannot execute ‘/home/REDACTED/test’: Permission denied (os error 13)

  ProblemType: Bug
  DistroRelease: Ubuntu 25.10
  Package: sudo-rs 0.2.8-1ubuntu5
  ProcVersionSignature: Ubuntu 6.17.0-6.6-generic 6.17.1
  Uname: Linux 6.17.0-6-generic x86_64
  ApportVersion: 2.33.1-0ubuntu3
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: Budgie
  Date: Sun Nov  9 09:25:14 2025
  InstallationDate: Installed on 2025-10-23 (17 days ago)
  InstallationMedia: Ubuntu-Budgie 25.04 "Plucky Puffin" - Release amd64 (20250415.2)
  ProcEnviron:
   LANG=en_GB.UTF-8
   PATH=(custom, no user)
   SHELL=/bin/bash
   TERM=xterm-256color
   XDG_RUNTIME_DIR=<set>
  SourcePackage: rust-sudo-rs
  UpgradeStatus: Upgraded to questing on 2025-11-02 (7 days ago)

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