Fwd: [merged] usercopy-mark-dma-kmalloc-caches-as-usercopy-caches.patch removed from -mm tree

[Christian Borntraeger]

stable team,
please consider 

commit 49f2d2419d60a103752e5fbaf158cf8d07c0d884
    usercopy: mark dma-kmalloc caches as usercopy caches
for stable.

-------- Forwarded Message --------
Subject: [merged] usercopy-mark-dma-kmalloc-caches-as-usercopy-caches.patch removed from -mm tree
Date: Tue, 02 Jun 2020 14:37:44 -0700
From: akpm@xxxxxxxxxxxxxxxxxxxx
To: borntraeger@xxxxxxxxxx, christoffer.dall@xxxxxxxxxx, cl@xxxxxxxxx, dave.kleikamp@xxxxxxxxxx, dave@xxxxxxxxxxxx, davem@xxxxxxxxxxxxx, hch@xxxxxxxxxxxxx, iamjoonsoo.kim@xxxxxxx, jack@xxxxxxx, jannh@xxxxxxxxxx, jslaby@xxxxxxx, jwi@xxxxxxxxxxxxx, labbott@xxxxxxxxxx, luisbg@xxxxxxxxxx, luto@xxxxxxxxxx, marc.zyngier@xxxxxxx, mark.rutland@xxxxxxx, martin.petersen@xxxxxxxxxx, mjg59@xxxxxxxxxx, mkubecek@xxxxxxx, mm-commits@xxxxxxxxxxxxxxx, pbonzini@xxxxxxxxxx, penberg@xxxxxxxxxx, riel@xxxxxxxxxxx, rientjes@xxxxxxxxxx, torvalds@xxxxxxxxxxxxxxxxxxxx, ubraun@xxxxxxxxxxxxx, vbabka@xxxxxxx, viro@xxxxxxxxxxxxxxxxxx


The patch titled
     Subject: usercopy: mark dma-kmalloc caches as usercopy caches
has been removed from the -mm tree.  Its filename was
     usercopy-mark-dma-kmalloc-caches-as-usercopy-caches.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: usercopy: mark dma-kmalloc caches as usercopy caches

We have seen a "usercopy: Kernel memory overwrite attempt detected to SLUB
object 'dma-kmalloc-1 k' (offset 0, size 11)!" error on s390x, as IUCV
uses kmalloc() with __GFP_DMA because of memory address restrictions.  The
issue has been discussed [2] and it has been noted that if all the kmalloc
caches are marked as usercopy, there's little reason not to mark
dma-kmalloc caches too.  The 'dma' part merely means that __GFP_DMA is
used to restrict memory address range.

As Jann Horn put it [3]:

"I think dma-kmalloc slabs should be handled the same way as normal
kmalloc slabs.  When a dma-kmalloc allocation is freshly created, it is
just normal kernel memory - even if it might later be used for DMA -, and
it should be perfectly fine to copy_from_user() into such allocations at
that point, and to copy_to_user() out of them at the end.  If you look at
the places where such allocations are created, you can see things like
kmemdup(), memcpy() and so on - all normal operations that shouldn't
conceptually be different from usercopy in any relevant way."

Thus this patch marks the dma-kmalloc-* caches as usercopy.

[1] https://bugzilla.suse.com/show_bug.cgi?id=1156053
[2] https://lore.kernel.org/kernel-hardening/bfca96db-bbd0-d958-7732-76e36c667c68@xxxxxxx/
[3] https://lore.kernel.org/kernel-hardening/CAG48ez1a4waGk9kB0WLaSbs4muSoK0AYAVk8=XYaKj4_+6e6Hg@xxxxxxxxxxxxxx/

Link: http://lkml.kernel.org/r/7d810f6d-8085-ea2f-7805-47ba3842dc50@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Acked-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: Julian Wiedmann <jwi@xxxxxxxxxxxxx>
Cc: Ursula Braun <ubraun@xxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: David Windsor <dave@xxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Cc: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Luis de Bethencourt <luisbg@xxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxx>
Cc: Michal Kubecek <mkubecek@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/slab_common.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/slab_common.c~usercopy-mark-dma-kmalloc-caches-as-usercopy-caches
+++ a/mm/slab_common.c
@@ -1303,7 +1303,8 @@ void __init create_kmalloc_caches(slab_f
 			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
_

Patches currently in -mm which might be from vbabka@xxxxxxx are

kernel-sysctl-support-setting-sysctl-parameters-from-kernel-command-line.patch
kernel-sysctl-support-handling-command-line-aliases.patch
kernel-hung_task-convert-hung_task_panic-boot-parameter-to-sysctl.patch
tools-testing-selftests-sysctl-sysctlsh-support-config_test_sysctl=y.patch
lib-test_sysctl-support-testing-of-sysctl-boot-parameter.patch
lib-test_sysctl-support-testing-of-sysctl-boot-parameter-fix.patch