kernel.git/arch/arm/mm, branch linux-3.10.y

mm: larger stack guard gap, between vmas

2017-06-21T13:42:43Z

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream. Stack guard page is a useful feature to reduce a risk of stack smashing into a different mapping. We have been using a single page gap which is sufficient to prevent having stack adjacent to a different mapping. But this seems to be insufficient in the light of the stack usage in userspace. E.g. glibc uses as large as 64kB alloca() in many commonly used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX] which is 256kB or stack strings with MAX_ARG_STRLEN. This will become especially dangerous for suid binaries and the default no limit for the stack size limit because those applications can be tricked to consume a large portion of the stack and a single glibc call could jump over the guard page. These attacks are not theoretical, unfortunatelly. Make those attacks less probable by increasing the stack guard gap to 1MB (on systems with 4k pages; but make it depend on the page size because systems with larger base pages might cap stack allocations in the PAGE_SIZE units) which should cover larger alloca() and VLA stack allocations. It is obviously not a full fix because the problem is somehow inherent, but it should reduce attack space a lot. One could argue that the gap size should be configurable from userspace, but that can be done later when somebody finds that the new 1MB is wrong for some special case applications. For now, add a kernel command line option (stack_guard_gap) to specify the stack gap size (in page units). Implementation wise, first delete all the old code for stack guard page: because although we could get away with accounting one extra page in a stack vma, accounting a larger gap can break userspace - case in point, a program run with "ulimit -S -v 20000" failed when the 1MB gap was counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK and strict non-overcommit mode. Instead of keeping gap inside the stack vma, maintain the stack guard gap as a gap between vmas: using vm_start_gap() in place of vm_start (or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few places which need to respect the gap - mainly arch_get_unmapped_area(), and and the vma tree's subtree_gap support for that. Original-patch-by: Oleg Nesterov Original-patch-by: Michal Hocko Signed-off-by: Hugh Dickins [wt: backport to 4.11: adjust context] [wt: backport to 4.9: adjust context ; kernel doc was not in admin-guide] [wt: backport to 4.4: adjust context ; drop ppc hugetlb_radix changes] [wt: backport to 3.18: adjust context ; no FOLL_POPULATE ; s390 uses generic arch_get_unmapped_area()] [wt: backport to 3.16: adjust context] [wt: backport to 3.10: adjust context ; code logic in PARISC's arch_get_unmapped_area() wasn't found ; code inserted into expand_upwards() and expand_downwards() runs under anon_vma lock; changes for gup.c:faultin_page go to memory.c:__get_user_pages(); included Hugh Dickins' fixes] Signed-off-by: Willy Tarreau

ARM: 8427/1: dma-mapping: add support for offset parameter in dma_mmap()

2015-12-09T18:40:07Z

commit 7e31210349e9e03a9a4dff31ab5f2bc83e8e84f5 upstream. IOMMU-based dma_mmap() implementation lacked proper support for offset parameter used in mmap call (it always assumed that mapping starts from offset zero). This patch adds support for offset parameter to IOMMU-based implementation. Signed-off-by: Marek Szyprowski Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: 8426/1: dma-mapping: add missing range check in dma_mmap()

2015-12-09T18:40:07Z

commit 371f0f085f629fc0f66695f572373ca4445a67ad upstream. dma_mmap() function in IOMMU-based dma-mapping implementation lacked a check for valid range of mmap parameters (offset and buffer size), what might have caused access beyond the allocated buffer. This patch fixes this issue. Signed-off-by: Marek Szyprowski Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: 8109/1: mm: Modify pte_write and pmd_write logic for LPAE

2015-02-06T06:35:39Z

commit ded9477984690d026e46dd75e8157392cea3f13f upstream. For LPAE, we have the following means for encoding writable or dirty ptes: L_PTE_DIRTY L_PTE_RDONLY !pte_dirty && !pte_write 0 1 !pte_dirty && pte_write 0 1 pte_dirty && !pte_write 1 1 pte_dirty && pte_write 1 0 So we can't distinguish between writeable clean ptes and read only ptes. This can cause problems with ptes being incorrectly flagged as read only when they are writeable but not dirty. This patch renumbers L_PTE_RDONLY from AP[2] to a software bit #58, and adds additional logic to set AP[2] whenever the pte is read only or not dirty. That way we can distinguish between clean writeable ptes and read only ptes. HugeTLB pages will use this new logic automatically. We need to add some logic to Transparent HugePages to ensure that they correctly interpret the revised pgprot permissions (L_PTE_RDONLY has moved and no longer matches PMD_SECT_AP2). In the process of revising THP, the names of the PMD software bits have been prefixed with L_ to make them easier to distinguish from their hardware bit counterparts. Signed-off-by: Steve Capper Reviewed-by: Will Deacon Signed-off-by: Russell King [hpy: Backported to 3.10 - adjust the context - ignore change related to pmd, because 3.10 does not support HugePage ] Signed-off-by: Hou Pengyang Signed-off-by: Greg Kroah-Hartman

ARM: DMA: ensure that old section mappings are flushed from the TLB

2015-02-06T06:35:39Z

commit 6b076991dca9817e75c37e2f0db6d52611ea42fa upstream. When setting up the CMA region, we must ensure that the old section mappings are flushed from the TLB before replacing them with page tables, otherwise we can suffer from mismatched aliases if the CPU speculatively prefetches from these mappings at an inopportune time. A mismatched alias can occur when the TLB contains a section mapping, but a subsequent prefetch causes it to load a page table mapping, resulting in the possibility of the TLB containing two matching mappings for the same virtual address region. Acked-by: Will Deacon Signed-off-by: Russell King Cc: Hou Pengyang Signed-off-by: Greg Kroah-Hartman

ARM: LPAE: use phys_addr_t in alloc_init_pud()

2015-02-06T06:35:38Z

commit 20d6956d8cd2452cec0889ff040f18afc03c2e6b upstream. This patch fixes the alloc_init_pud() function to use phys_addr_t instead of unsigned long when passing in the phys argument. This is an extension to commit 97092e0c56830457af0639f6bd904537a150ea4a (ARM: pgtable: use phys_addr_t for physical addresses), which applied similar changes elsewhere in the ARM memory management code. Signed-off-by: Vitaly Andrianov Signed-off-by: Cyril Chemparathy Acked-by: Nicolas Pitre Acked-by: Catalin Marinas Tested-by: Santosh Shilimkar Tested-by: Subash Patel Signed-off-by: Will Deacon Cc: Hou Pengyang Signed-off-by: Greg Kroah-Hartman

ARM: 8222/1: mvebu: enable strex backoff delay

2014-12-06T23:05:49Z

commit 995ab5189d1d7264e79e665dfa032a19b3ac646e upstream. Under extremely rare conditions, in an MPCore node consisting of at least 3 CPUs, two CPUs trying to perform a STREX to data on the same shared cache line can enter a livelock situation. This patch enables the HW mechanism that overcomes the bug. This fixes the incorrect setup of the STREX backoff delay bit due to a wrong description in the specification. Note that enabling the STREX backoff delay mechanism is done by leaving the bit *cleared*, while the bit was currently being set by the proc-v7.S code. [Thomas: adapt to latest mainline, slightly reword the commit log, add stable markers.] Fixes: de4901933f6d ("arm: mm: Add support for PJ4B cpu and init routines") Signed-off-by: Nadav Haklai Signed-off-by: Thomas Petazzoni Acked-by: Gregory CLEMENT Acked-by: Jason Cooper Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

ARM: 8216/1: xscale: correct auxiliary register in suspend/resume

2014-12-06T23:05:48Z

commit ef59a20ba375aeb97b3150a118318884743452a8 upstream. According to the manuals I have, XScale auxiliary register should be reached with opc_2 = 1 instead of crn = 1. cpu_xscale_proc_init correctly uses c1, c0, 1 arguments, but cpu_xscale_do_suspend and cpu_xscale_do_resume use c1, c1, 0. Correct suspend/resume functions to also use c1, c0, 1. The issue was primarily noticed thanks to qemu reporing "unsupported instruction" on the pxa suspend path. Confirmed in PXA210/250 and PXA255 XScale Core manuals and in PXA270 and PXA320 Developers Guides. Harware tested by me on tosa (pxa255). Robert confirmed on pxa270 board. Tested-by: Robert Jarzmik Signed-off-by: Dmitry Eremin-Solenikov Acked-by: Robert Jarzmik Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman

arch: mm: pass userspace fault flag to generic fault handler

2014-11-21T17:22:56Z

commit 759496ba6407c6994d6a5ce3a5e74937d7816208 upstream. Unlike global OOM handling, memory cgroup code will invoke the OOM killer in any OOM situation because it has no way of telling faults occuring in kernel context - which could be handled more gracefully - from user-triggered faults. Pass a flag that identifies faults originating in user space from the architecture-specific fault handlers to generic code so that memcg OOM handling can be improved. Signed-off-by: Johannes Weiner Reviewed-by: Michal Hocko Cc: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: azurIt Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Cong Wang Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

arch: mm: do not invoke OOM killer on kernel fault OOM

2014-11-21T17:22:55Z

commit 871341023c771ad233620b7a1fb3d9c7031c4e5c upstream. Kernel faults are expected to handle OOM conditions gracefully (gup, uaccess etc.), so they should never invoke the OOM killer. Reserve this for faults triggered in user context when it is the only option. Most architectures already do this, fix up the remaining few. Signed-off-by: Johannes Weiner Reviewed-by: Michal Hocko Acked-by: KOSAKI Motohiro Cc: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: azurIt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Cong Wang Signed-off-by: Greg Kroah-Hartman