On Thu, Aug 15, 2019 at 12:35:26PM +0200, Knut Omang wrote:
On Thu, 2019-08-15 at 10:49 +0200, Greg Kroah-Hartman wrote:
I perfectly agree with you that reducing the hole for a race condition is generally a bad idea, but from the above mail thread it seems that's the only available choice for older kernels?
I have no idea, but please, do not use that pattern of code as it is racy in all kernels, from all of time.
Ok, will remove it :-)
I tried in vain to find the commit from Al Viro that made the code safe, to identify which kernels that are safe from this issue, but he has a **lot** of commits, do you have a clue for what/where to look?
It will be good to have a mention/comment on this for future reference, like the earliest kernel version where this is safe.
Always use a "newer" kernel to be "safe" and you will be fine :)
Maybe we can even get rid of some more of the remaining of these too.. (I notice there's 65 cases of 'if (!try_module_get(THIS_MODULE))' right now)
Something to put on a TODO list somewhere...