On Thu, 3 Nov 2022 at 18:04, Peter Griffin peter.griffin@linaro.org wrote:
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
Looks good.
Acked-by: Miklos Szeredi mszeredi@redhat.com
Thanks, Miklos