Messages in this thread | | | Date | Mon, 13 Aug 2007 13:53:02 +0400 | From | Cyrill Gorcunov <> | Subject | Re: [BUGFIX] NULL pointer dereference in __vm_enough_memory() |
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[WU Fengguang - Mon, Aug 13, 2007 at 08:23:42AM +0800] | On Sun, Aug 12, 2007 at 08:21:43PM +0400, Cyrill Gorcunov wrote: | > [Alan Cox - Sun, Aug 12, 2007 at 04:17:44PM +0100] | > | Try this (it compiles but isnt tested). Its a weekend here, the sun is | > | shining, the beach is a short walk, and I have more interesting things to | > | do right now 8) | > | | > | | [...] | > | -int __vm_enough_memory(long pages, int cap_sys_admin) | > | +int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) | > | { | > | unsigned long free, allowed; | > | | > | @@ -166,7 +166,7 @@ | > | | > | /* Don't let a single process grow too big: | > | leave 3% of the size of this process for other processes */ | > | - allowed -= current->mm->total_vm / 32; | > | + allowed -= mm->total_vm / 32; | > | > So mm->total_vm is 0 for __bprm_mm_init case. Is that ok? Or I miss | > something? | | Yeah, Alan adds mm to the interfaces and leaves us the question of | "what mm to pass in when current->mm == NULL?" ;) |
Well, as I see, it seems the Alan's patch is correct. We pass newly created mm to security_vm_enough_memory_mm() and get no errors here even for overcommit = 2. But my question was that mm->total_vm = 0 for this case and that is probably valid too I think. What about the thing you pointed about? Well I think security_vm_enough_memory should never be called from kernel thread (we have secrurity_vm_enough_memory_mm for this). But I will check it more closely. Dont get me wrong - I'm not VMM expert and may do errors ;)
Cyrill
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