Messages in this thread Patch in this message | | | Date | Wed, 22 Aug 2007 11:48:52 +0300 | From | Dan Aloni <> | Subject | Re: [patch 3/3] mm: variable length argument support |
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On Wed, Jun 13, 2007 at 12:03:37PM +0200, Peter Zijlstra wrote: > From: Ollie Wild <aaw@google.com> > > Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly > from the old mm into the new mm. > [...] > +static int __bprm_mm_init(struct linux_binprm *bprm) > +{ [...] > + vma->vm_flags = VM_STACK_FLAGS; > + vma->vm_page_prot = protection_map[vma->vm_flags & 0x7]; > + err = insert_vm_struct(mm, vma); > + if (err) { > + up_write(&mm->mmap_sem); > + goto err; > + } > +
That change causes a crash in khelper when overcommit_memory = 2 under 2.6.23-rc3.
When a khelper execs, at __bprm_mm_init() current->mm is still NULL. insert_vm_struct() calls security_vm_enough_memory(), which calls __vm_enough_memory(), and that's where current->mm->total_vm gets dereferenced.
Signed-off-by: Dan Aloni <da-x@monatomic.org>
diff --git a/mm/mmap.c b/mm/mmap.c index 906ed40..6e021df 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -163,10 +163,12 @@ int __vm_enough_memory(long pages, int cap_sys_admin) if (!cap_sys_admin) allowed -= allowed / 32; allowed += total_swap_pages; - - /* 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; + + if (current->mm) { + /* 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; + } /* * cast `allowed' as a signed long because vm_committed_space
-- Dan Aloni XIV LTD, http://www.xivstorage.com da-x (at) monatomic.org, dan (at) xiv.co.il - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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