On Mon, Sep 02, 2024 at 08:19:33AM +0200, Christophe Leroy wrote: > > > Le 02/09/2024 à 07:31, Omar Sandoval a écrit : > > [Vous ne recevez pas souvent de courriers de osandov@xxxxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ] > > > > From: Omar Sandoval <osandov@xxxxxx> > > > > Hi, > > > > I hit a case where copy_to_kernel_nofault() will fault (lol): if the > > destination address is in userspace and x86 Supervisor Mode Access > > Prevention is enabled. Patch 2 has the details and the fix. Patch 1 > > renames a helper function so that its use in patch 2 makes more sense. > > If the rename is too intrusive, I can drop it. > > The name of the function is "copy_to_kernel". If the destination is a user > address, it is not a copy to kernel but a copy to user and you already have > the function copy_to_user() for that. copy_to_user() properly handles SMAP. I'm not trying to copy to user. I am (well, KDB is) trying to copy to an arbitrary address, and I want it to return an error instead of crashing if the address is not a valid kernel address. As far as I can tell, that is the whole point of copy_to_kernel_nofault(). Thanks, Omar
