The patch below does not apply to the 6.11-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.11.y git checkout FETCH_HEAD git cherry-pick -x 2714b0d1f36999dbd99a3474a24e7301acbd74f1 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024120203-carat-landlord-afcf@gregkh' --subject-prefix 'PATCH 6.11.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2714b0d1f36999dbd99a3474a24e7301acbd74f1 Mon Sep 17 00:00:00 2001 From: Christian Brauner brauner@kernel.org Date: Tue, 8 Oct 2024 13:30:49 +0200 Subject: [PATCH] fcntl: make F_DUPFD_QUERY associative

Currently when passing a closed file descriptor to fcntl(fd, F_DUPFD_QUERY, fd_dup) the order matters:

fd = open("/dev/null"); fd_dup = dup(fd);

When we now close one of the file descriptors we get:

(1) fcntl(fd, fd_dup) // -EBADF (2) fcntl(fd_dup, fd) // 0 aka not equal

depending on which file descriptor is passed first. That's not a huge deal but it gives the api I slightly weird feel. Make it so that the order doesn't matter by requiring that both file descriptors are valid:

(1') fcntl(fd, fd_dup) // -EBADF (2') fcntl(fd_dup, fd) // -EBADF

Link: https://lore.kernel.org/r/20241008-duften-formel-251f967602d5@brauner Fixes: c62b758bae6a ("fcntl: add F_DUPFD_QUERY fcntl()") Reviewed-by: Jeff Layton jlayton@kernel.org Reviewed-By: Lennart Poettering lennart@poettering.net Cc: stable@vger.kernel.org Reported-by: Lennart Poettering lennart@poettering.net Signed-off-by: Christian Brauner brauner@kernel.org

diff --git a/fs/fcntl.c b/fs/fcntl.c index 22dd9dcce7ec..3d89de31066a 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -397,6 +397,9 @@ static long f_dupfd_query(int fd, struct file *filp) { CLASS(fd_raw, f)(fd);

+ if (fd_empty(f)) + return -EBADF; + /* * We can do the 'fdput()' immediately, as the only thing that * matters is the pointer value which isn't changed by the fdput.