Resending this because stable@vger.kernel.org using wrong header field. Apologize for duplicates.

On Thu, 19 May 2022 09:52:07 -0400 Sasha Levin sashal@kernel.org wrote:

This is a note to let you know that I've just added the patch titled

um: port_user: Improve error handling when port-helper is not found

to the 5.17-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: um-port_user-improve-error-handling-when-port-helper.patch and it can be found in the queue-5.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

First, I should say that I'm not familiar with the process so I'm likely to be wrong on any number of things. Second I'm the author of this patch and I would like to see this included in the stable trees. However, it appears to me that there is a problem in including just this patch, as it depends on a previous patch which does not appear to be applied[1].

commit efc324ad7e7e1c92a8862bd71b2f5f8f15513304 Author: Glenn Washburn development@efficientek.com Date: Thu Mar 3 01:53:32 2022 -0600

um: port_user: Improve error handling when port-helper is not found

[ Upstream commit 3cb5a7f167c620a8b0e38b0446df2e024d2243dc ] Check if port-helper exists and is executable. If not, write an error message to the kernel log with information to help the user diagnose the issue and exit with an error. If UML_PORT_HELPER was not set, write a message suggesting that the user set it. This makes it easier to understand why telneting to the UML instance is failing and what can be done to fix it. Signed-off-by: Glenn Washburn development@efficientek.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Sasha Levin sashal@kernel.org

diff --git a/arch/um/drivers/port_user.c b/arch/um/drivers/port_user.c index 5b5b64cb1071..133ca7bf2d91 100644 --- a/arch/um/drivers/port_user.c +++ b/arch/um/drivers/port_user.c @@ -5,6 +5,7 @@ #include <stdio.h> #include <stdlib.h> +#include <string.h> #include <errno.h> #include <termios.h> #include <unistd.h> @@ -175,6 +176,17 @@ int port_connection(int fd, int *socket, int *pid_out) if (new < 0) return -errno;

• err = os_access(argv[2], X_OK);
• if (err < 0) {

• printk(UM_KERN_ERR "port_connection : error accessing port-helper "
  

•        "executable at %s: %s\n", argv[2], strerror(-err));
  

• if (env == NULL)
  

The the afore mentioned patch that this patch depends on "env" is declared and set. Without it, I'd expect this to fail to compile. As such, I may be wrong in that the dependent patch was not already included because I'd expect there to have been a compile test prior to this patch getting to this phase.

My suspicion is that the stable trees try to not include new functionality, which the missing patch may have been considered to have done, and thus was not included. If its deemed undesirable to include the missing patch, this "if" block can be removed. Although, I think the missing patch is valuable enough to include.

The above goes for all the stable branches that this patch is set to be included in.

Glenn

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h...

• 	printk(UM_KERN_ERR "Set UML_PORT_HELPER environment "
  

• 		"variable to path to uml-utilities port-helper "
  

• 		"binary\n");
  

• goto out_close;
  

• }
• err = os_pipe(socket, 0, 0); if (err < 0) goto out_close;