On Thu, Feb 28, 2019 at 10:07:26AM -0500, Sasha Levin wrote:
From: Greg Kroah-Hartman gregkh@linuxfoundation.org
[ Upstream commit ff9fb72bc07705c00795ca48631f7fffe24d2c6b ]
When an error happens, debugfs should return an error pointer value, not NULL. This will prevent the totally theoretical error where a debugfs call fails due to lack of memory, returning NULL, and that dentry value is then passed to another debugfs call, which would end up succeeding, creating a file at the root of the debugfs tree, but would then be impossible to remove (because you can not remove the directory NULL).
So, to make everyone happy, always return errors, this makes the users of debugfs much simpler (they do not have to ever check the return value), and everyone can rest easy.
Reported-by: Gary R Hook ghook@amd.com Reported-by: Heiko Carstens heiko.carstens@de.ibm.com Reported-by: Masami Hiramatsu mhiramat@kernel.org Reported-by: Michal Hocko mhocko@kernel.org Reported-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Reported-by: Ulf Hansson ulf.hansson@linaro.org Reviewed-by: Masami Hiramatsu mhiramat@kernel.org Reviewed-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org
fs/debugfs/inode.c | 39 ++++++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 17 deletions(-)
As much as I would love to backport this patch, no, please do not, I did not mark it for stable on purpose. It can cause regressions with code that is not expecting this behavior (I have a fix that needs to go into 5.0 for this very reason.)
Please drop it from all queues.
thanks,
greg k-h