* Fwd: [merged] usercopy-mark-dma-kmalloc-caches-as-usercopy-caches.patch removed from -mm tree
[not found] <20200602213744.63kb6HfFG%akpm@linux-foundation.org>
@ 2020-06-15 13:24 ` Christian Borntraeger
2020-06-15 13:27 ` Greg KH
0 siblings, 1 reply; 2+ messages in thread
From: Christian Borntraeger @ 2020-06-15 13:24 UTC (permalink / raw)
To: stable; +Cc: Vlastimil Babka, linux-kernel
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@linux-foundation.org
To: borntraeger@de.ibm.com, christoffer.dall@linaro.org, cl@linux.com, dave.kleikamp@oracle.com, dave@nullcore.net, davem@davemloft.net, hch@infradead.org, iamjoonsoo.kim@lge.com, jack@suse.cz, jannh@google.com, jslaby@suse.cz, jwi@linux.ibm.com, labbott@redhat.com, luisbg@kernel.org, luto@kernel.org, marc.zyngier@arm.com, mark.rutland@arm.com, martin.petersen@oracle.com, mjg59@google.com, mkubecek@suse.cz, mm-commits@vger.kernel.org, pbonzini@redhat.com, penberg@kernel.org, riel@surriel.com, rientjes@google.com, torvalds@linux-foundation.org, ubraun@linux.ibm.com, vbabka@suse.cz, viro@zeniv.linux.org.uk
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@suse.cz>
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@suse.cz/
[3] https://lore.kernel.org/kernel-hardening/CAG48ez1a4waGk9kB0WLaSbs4muSoK0AYAVk8=XYaKj4_+6e6Hg@mail.gmail.com/
Link: http://lkml.kernel.org/r/7d810f6d-8085-ea2f-7805-47ba3842dc50@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christopher Lameter <cl@linux.com>
Cc: Julian Wiedmann <jwi@linux.ibm.com>
Cc: Ursula Braun <ubraun@linux.ibm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Windsor <dave@nullcore.net>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Luis de Bethencourt <luisbg@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Matthew Garrett <mjg59@google.com>
Cc: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
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@suse.cz 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
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