Thomas Weißschuh bc7372c05a fs: always return zero on success from replace_fd()
commit 708c04a5c2 upstream.

replace_fd() returns the number of the new file descriptor through the
return value of do_dup2(). However its callers never care about the
specific returned number. In fact the caller in receive_fd_replace() treats
any non-zero return value as an error and therefore never calls
__receive_sock() for most file descriptors, which is a bug.

To fix the bug in receive_fd_replace() and to avoid the same issue
happening in future callers, signal success through a plain zero.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/lkml/20250801220215.GS222315@ZenIV/
Fixes: 173817151b ("fs: Expand __receive_fd() to accept existing fd")
Fixes: 42eb0d54c0 ("fs: split receive_fd_replace from __receive_fd")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://lore.kernel.org/20250805-fix-receive_fd_replace-v3-1-b72ba8b34bac@linutronix.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-10-19 16:30:39 +02:00
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2025-10-15 11:58:10 +02:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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