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-d958-7732-76e36c667c6... [3] https://lore.kernel.org/kernel-hardening/CAG48ez1a4waGk9kB0WLaSbs4muSoK0AYAV...

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