Peter Griffin 406c706c7b vfs: vfs_tmpfile: ensure O_EXCL flag is enforced
If O_EXCL is *not* specified, then linkat() can be
used to link the temporary file into the filesystem.
If O_EXCL is specified then linkat() should fail (-1).

After commit 863f144f12ad ("vfs: open inside ->tmpfile()")
the O_EXCL flag is no longer honored by the vfs layer for
tmpfile, which means the file can be linked even if O_EXCL
flag is specified, which is a change in behaviour for
userspace!

The open flags was previously passed as a parameter, so it
was uneffected by the changes to file->f_flags caused by
finish_open(). This patch fixes the issue by storing
file->f_flags in a local variable so the O_EXCL test
logic is restored.

This regression was detected by Android CTS Bionic fcntl()
tests running on android-mainline [1].

[1] https://android.googlesource.com/platform/bionic/+/
    refs/heads/master/tests/fcntl_test.cpp#352

Fixes: 863f144f12ad ("vfs: open inside ->tmpfile()")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2022-11-19 02:22:11 -05:00
2022-09-28 09:02:20 +02:00
2022-10-12 14:46:48 -07:00
2022-10-16 11:12:22 -07:00
2022-10-14 13:22:14 -07:00
2022-10-12 14:46:48 -07:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2022-08-03 19:52:08 -07:00
2022-10-10 12:00:45 -07:00
2022-10-15 16:47:33 -07:00
2022-10-16 15:36:24 -07:00

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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