| Message ID | 20220612213227.3881769-2-willy@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Fixes for usercopy | expand |
> vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > us to deny usercopies from those areas. This affects XFS which uses > vm_map_ram() for its directories. > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > include/linux/vmalloc.h | 1 + > mm/usercopy.c | 8 +++++--- > mm/vmalloc.c | 2 +- > 3 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index b159c2789961..096d48aa3437 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -215,6 +215,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size, > void free_vm_area(struct vm_struct *area); > extern struct vm_struct *remove_vm_area(const void *addr); > extern struct vm_struct *find_vm_area(const void *addr); > +struct vmap_area *find_vmap_area(unsigned long addr); Make it "extern" since it becomes globally visible? -- Uladzislau Rezki
On 06/13/22 at 12:00pm, Uladzislau Rezki wrote: > > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > > us to deny usercopies from those areas. This affects XFS which uses > > vm_map_ram() for its directories. > > > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > > > Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > --- > > include/linux/vmalloc.h | 1 + > > mm/usercopy.c | 8 +++++--- > > mm/vmalloc.c | 2 +- > > 3 files changed, 7 insertions(+), 4 deletions(-) > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > index b159c2789961..096d48aa3437 100644 > > --- a/include/linux/vmalloc.h > > +++ b/include/linux/vmalloc.h > > @@ -215,6 +215,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size, > > void free_vm_area(struct vm_struct *area); > > extern struct vm_struct *remove_vm_area(const void *addr); > > extern struct vm_struct *find_vm_area(const void *addr); > > +struct vmap_area *find_vmap_area(unsigned long addr); > Make it "extern" since it becomes globally visible? extern is not suggested any more to add for function declaration in header file, and removing it doesn't impact thing. > > -- > Uladzislau Rezki >
> On 06/13/22 at 12:00pm, Uladzislau Rezki wrote: > > > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > > > us to deny usercopies from those areas. This affects XFS which uses > > > vm_map_ram() for its directories. > > > > > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > > > > > Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") > > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > > > --- > > > include/linux/vmalloc.h | 1 + > > > mm/usercopy.c | 8 +++++--- > > > mm/vmalloc.c | 2 +- > > > 3 files changed, 7 insertions(+), 4 deletions(-) > > > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > > index b159c2789961..096d48aa3437 100644 > > > --- a/include/linux/vmalloc.h > > > +++ b/include/linux/vmalloc.h > > > @@ -215,6 +215,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size, > > > void free_vm_area(struct vm_struct *area); > > > extern struct vm_struct *remove_vm_area(const void *addr); > > > extern struct vm_struct *find_vm_area(const void *addr); > > > +struct vmap_area *find_vmap_area(unsigned long addr); > > Make it "extern" since it becomes globally visible? > > extern is not suggested any more to add for function declaration in > header file, and removing it doesn't impact thing. > OK, thanks for the hint: Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com> -- Uladzislau Rezki
On Sun, Jun 12, 2022 at 10:32:25PM +0100, Matthew Wilcox (Oracle) wrote: > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > us to deny usercopies from those areas. This affects XFS which uses > vm_map_ram() for its directories. > > Fix this by calling find_vmap_area() instead of find_vm_area(). Thanks for the fixes! > [...] > + /* XXX: We should also abort for free vmap_areas */ What's needed to detect this?
On Mon, Jun 13, 2022 at 09:23:15AM -0700, Kees Cook wrote: > On Sun, Jun 12, 2022 at 10:32:25PM +0100, Matthew Wilcox (Oracle) wrote: > > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > > us to deny usercopies from those areas. This affects XFS which uses > > vm_map_ram() for its directories. > > > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > Thanks for the fixes! > > > [...] > > + /* XXX: We should also abort for free vmap_areas */ > > What's needed to detect this? I'm not entirely sure. I only just learned of the existence of this struct ;-) /* * The following two variables can be packed, because * a vmap_area object can be either: * 1) in "free" tree (root is free_vmap_area_root) * 2) or "busy" tree (root is vmap_area_root) */ union { unsigned long subtree_max_size; /* in "free" tree */ struct vm_struct *vm; /* in "busy" tree */ }; Hmm. Actually, we only search vmap_area_root, so I suppose it can't be a free area. So this XXX can be removed, as we'll get NULL back if we've got a pointer to a free area. Ulad, do I have this right?
On Mon, Jun 13, 2022 at 05:44:35PM +0100, Matthew Wilcox wrote: > On Mon, Jun 13, 2022 at 09:23:15AM -0700, Kees Cook wrote: > > On Sun, Jun 12, 2022 at 10:32:25PM +0100, Matthew Wilcox (Oracle) wrote: > > > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > > > us to deny usercopies from those areas. This affects XFS which uses > > > vm_map_ram() for its directories. > > > > > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > > > Thanks for the fixes! > > > > > [...] > > > + /* XXX: We should also abort for free vmap_areas */ > > > > What's needed to detect this? > > I'm not entirely sure. I only just learned of the existence of this > struct ;-) > > /* > * The following two variables can be packed, because > * a vmap_area object can be either: > * 1) in "free" tree (root is free_vmap_area_root) > * 2) or "busy" tree (root is vmap_area_root) > */ > union { > unsigned long subtree_max_size; /* in "free" tree */ > struct vm_struct *vm; /* in "busy" tree */ > }; > > Hmm. Actually, we only search vmap_area_root, so I suppose it can't > be a free area. So this XXX can be removed, as we'll get NULL back > if we've got a pointer to a free area. Ulad, do I have this right? > Yep, we find here only allocated areas which bind to the "vmap_area_root" tree, so it can not be a freed area. So we will not get a pointer to the free area :) -- Uladzislau Rezki
On Mon, Jun 13, 2022 at 07:02:10PM +0200, Uladzislau Rezki wrote: > On Mon, Jun 13, 2022 at 05:44:35PM +0100, Matthew Wilcox wrote: > > On Mon, Jun 13, 2022 at 09:23:15AM -0700, Kees Cook wrote: > > > On Sun, Jun 12, 2022 at 10:32:25PM +0100, Matthew Wilcox (Oracle) wrote: > > > > vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes > > > > us to deny usercopies from those areas. This affects XFS which uses > > > > vm_map_ram() for its directories. > > > > > > > > Fix this by calling find_vmap_area() instead of find_vm_area(). > > > > > > Thanks for the fixes! > > > > > > > [...] > > > > + /* XXX: We should also abort for free vmap_areas */ > > > > > > What's needed to detect this? > > > > I'm not entirely sure. I only just learned of the existence of this > > struct ;-) > > > > /* > > * The following two variables can be packed, because > > * a vmap_area object can be either: > > * 1) in "free" tree (root is free_vmap_area_root) > > * 2) or "busy" tree (root is vmap_area_root) > > */ > > union { > > unsigned long subtree_max_size; /* in "free" tree */ > > struct vm_struct *vm; /* in "busy" tree */ > > }; > > > > Hmm. Actually, we only search vmap_area_root, so I suppose it can't > > be a free area. So this XXX can be removed, as we'll get NULL back > > if we've got a pointer to a free area. Ulad, do I have this right? > > > Yep, we find here only allocated areas which bind to the "vmap_area_root" > tree, so it can not be a freed area. So we will not get a pointer to the > free area :) Thanks! I've tweaked the patch to drop the XXX comment.
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index b159c2789961..096d48aa3437 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -215,6 +215,7 @@ extern struct vm_struct *__get_vm_area_caller(unsigned long size, void free_vm_area(struct vm_struct *area); extern struct vm_struct *remove_vm_area(const void *addr); extern struct vm_struct *find_vm_area(const void *addr); +struct vmap_area *find_vmap_area(unsigned long addr); static inline bool is_vm_area_hugepages(const void *addr) { diff --git a/mm/usercopy.c b/mm/usercopy.c index baeacc735b83..fdd1bed3b90a 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -173,7 +173,7 @@ static inline void check_heap_object(const void *ptr, unsigned long n, } if (is_vmalloc_addr(ptr)) { - struct vm_struct *area = find_vm_area(ptr); + struct vmap_area *area = find_vmap_area((unsigned long)ptr); unsigned long offset; if (!area) { @@ -181,8 +181,10 @@ static inline void check_heap_object(const void *ptr, unsigned long n, return; } - offset = ptr - area->addr; - if (offset + n > get_vm_area_size(area)) + /* XXX: We should also abort for free vmap_areas */ + + offset = (unsigned long)ptr - area->va_start; + if ((unsigned long)ptr + n > area->va_end) usercopy_abort("vmalloc", NULL, to_user, offset, n); return; } diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 07db42455dd4..effd1ff6a4b4 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1798,7 +1798,7 @@ static void free_unmap_vmap_area(struct vmap_area *va) free_vmap_area_noflush(va); } -static struct vmap_area *find_vmap_area(unsigned long addr) +struct vmap_area *find_vmap_area(unsigned long addr) { struct vmap_area *va;
vmalloc does not allocate a vm_struct for vm_map_ram() areas. That causes us to deny usercopies from those areas. This affects XFS which uses vm_map_ram() for its directories. Fix this by calling find_vmap_area() instead of find_vm_area(). Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- include/linux/vmalloc.h | 1 + mm/usercopy.c | 8 +++++--- mm/vmalloc.c | 2 +- 3 files changed, 7 insertions(+), 4 deletions(-)