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Date: Thu, 15 May 2014 11:18:29 +0800 From: Hillf Danton <dhillf@...il.com> To: Andy Lutomirski <luto@...capital.net> Cc: x86@...nel.org, Andrew Morton <akpm@...ux-foundation.org>, Sasha Levin <sasha.levin@...cle.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>, Dave Jones <davej@...hat.com>, LKML <linux-kernel@...r.kernel.org>, Stefani Seibold <stefani@...bold.net> Subject: Re: [PATCH v2 -next] x86,vdso: Fix an OOPS accessing the hpet mapping w/o an hpet Hi Andy, On Thu, May 15, 2014 at 7:46 AM, Andy Lutomirski <luto@...capital.net> wrote: > The oops can be triggered in qemu using -no-hpet (but not nohpet) by > reading a couple of pages past the end of the vdso text. This > should send SIGBUS instead of OOPSing. > > The bug was introduced by: > > commit 7a59ed415f5b57469e22e41fc4188d5399e0b194 > Author: Stefani Seibold <stefani@...bold.net> > Date: Mon Mar 17 23:22:09 2014 +0100 > > x86, vdso: Add 32 bit VDSO time support for 32 bit kernel > > which is new in 3.15. > > This will be fixed separately in 3.15, but that patch will not apply > to tip/x86/vdso. This is the equivalent fix for tip/x86/vdso and, > presumably, 3.16. > > Cc: Stefani Seibold <stefani@...bold.net> > Reported-by: Sasha Levin <sasha.levin@...cle.com> > Signed-off-by: Andy Lutomirski <luto@...capital.net> > --- > arch/x86/vdso/vma.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c > index e915eae..8ad0081 100644 > --- a/arch/x86/vdso/vma.c > +++ b/arch/x86/vdso/vma.c > @@ -90,6 +90,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr) > struct vm_area_struct *vma; > unsigned long addr; > int ret = 0; > + static struct page *no_pages[] = {NULL}; > > if (calculate_addr) { > addr = vdso_addr(current->mm->start_stack, > @@ -125,7 +126,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr) > addr + image->size, > image->sym_end_mapping - image->size, > VM_READ, > - NULL); > + no_pages); > > if (IS_ERR(vma)) { > ret = PTR_ERR(vma); > -- > 1.9.0 > As the comment says, /* * Called with mm->mmap_sem held for writing. * Insert a new vma covering the given region, with the given flags. * Its pages are supplied by the given array of struct page *. * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. * The region past the last page supplied will always produce SIGBUS. * The array pointer and the pages it points to are assumed to stay alive * for as long as this mapping might exist. */ struct vm_area_struct *_install_special_mapping(struct mm_struct *mm, unsigned long addr, unsigned long len, unsigned long vm_flags, struct page **pages) { we can send sigbus at fault time if no pages are supplied at install time. thanks Hillf -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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