Messages in this thread Patch in this message | | | Subject | Re: [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches | From | Jiri Slaby <> | Date | Tue, 12 Nov 2019 08:17:57 +0100 |
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On 11. 01. 18, 3:02, Kees Cook wrote: > From: David Windsor <dave@nullcore.net> > > Mark the kmalloc slab caches as entirely whitelisted. These caches > are frequently used to fulfill kernel allocations that contain data > to be copied to/from userspace. Internal-only uses are also common, > but are scattered in the kernel. For now, mark all the kmalloc caches > as whitelisted. > > This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY > whitelisting code in the last public patch of grsecurity/PaX based on my > understanding of the code. Changes or omissions from the original code are > mine and don't reflect the original grsecurity/PaX code. > > Signed-off-by: David Windsor <dave@nullcore.net> > [kees: merged in moved kmalloc hunks, adjust commit log] > Cc: Pekka Enberg <penberg@kernel.org> > Cc: David Rientjes <rientjes@google.com> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-mm@kvack.org > Cc: linux-xfs@vger.kernel.org > Signed-off-by: Kees Cook <keescook@chromium.org> > Acked-by: Christoph Lameter <cl@linux.com> > --- > mm/slab.c | 3 ++- > mm/slab.h | 3 ++- > mm/slab_common.c | 10 ++++++---- > 3 files changed, 10 insertions(+), 6 deletions(-) > > diff --git a/mm/slab.c b/mm/slab.c > index b9b0df620bb9..dd367fe17a4e 100644 > --- a/mm/slab.c > +++ b/mm/slab.c ... > @@ -1098,7 +1099,8 @@ void __init setup_kmalloc_cache_index_table(void) > static void __init new_kmalloc_cache(int idx, slab_flags_t flags) > { > kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name, > - kmalloc_info[idx].size, flags); > + kmalloc_info[idx].size, flags, 0, > + kmalloc_info[idx].size); > } > > /* > @@ -1139,7 +1141,7 @@ void __init create_kmalloc_caches(slab_flags_t flags) > > BUG_ON(!n); > kmalloc_dma_caches[i] = create_kmalloc_cache(n, > - size, SLAB_CACHE_DMA | flags); > + size, SLAB_CACHE_DMA | flags, 0, 0);
Hi,
was there any (undocumented) reason NOT to mark DMA caches as usercopy?
We are seeing this on s390x:
> usercopy: Kernel memory overwrite attempt detected to SLUB object 'dma-kmalloc-1k' (offset 0, size 11)! > ------------[ cut here ]------------ > kernel BUG at mm/usercopy.c:99!
See: https://bugzilla.suse.com/show_bug.cgi?id=1156053
This indeed fixes it: --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1290,7 +1290,8 @@ void __init create_kmalloc_caches(slab_flags_t flags) kmalloc_caches[KMALLOC_DMA][i] = create_kmalloc_cache( kmalloc_info[i].name[KMALLOC_DMA], kmalloc_info[i].size, - SLAB_CACHE_DMA | flags, 0, 0); + SLAB_CACHE_DMA | flags, 0, + kmalloc_info[i].size); } } #endif
thanks, -- js suse labs
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