Messages in this thread | | | From | Ohad Ben-Cohen <> | Date | Fri, 26 Nov 2010 12:16:39 +0200 | Subject | Re: [PATCH v2 1/4] drivers: hwspinlock: add generic framework |
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On Fri, Nov 26, 2010 at 11:18 AM, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: > On Fri, Nov 26, 2010 at 10:53:10AM +0200, Ohad Ben-Cohen wrote: >> >> +int __hwspin_trylock(struct hwspinlock *hwlock, int mode, unsigned long *flags) >> >> +{ >> >> + int ret; >> >> + >> >> + if (unlikely(!hwlock)) { >> >> + pr_err("invalid hwlock\n"); >> > >> > These kind of errors can get very spammy for buggy drivers. >> >> Yeah, but that's the purpose - I want to catch such egregious drivers >> who try to crash the kernel. > > That can be better - because you get a backtrace, and it causes people > to report the problem rather than just ignore it. It may also prevent > the driver author releasing his code (as it won't work on their > initial testing.) > ... > > If it's "extremely buggy behaviour" then the drivers deserve to crash. > Such stuff should cause them not to get out the door. A simple printk > with an error return can just be ignored.
I like this approach too, but recently we had a few privilege escalation exploits which involved NULL dereference kernel bugs (process context mapped address 0 despite a positive mmap_min_addr).
Since we can't rely on the oops to always happen, I decided not to omit the NULL checks.
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