kernel.git/mm/mmap.c, branch linux-5.19.y

mm/mmap: undo ->mmap() when arch_validate_flags() fails

2022-10-24T07:56:48Z

commit deb0f6562884b5b4beb883d73e66a7d3a1b96d99 upstream. Commit c462ac288f2c ("mm: Introduce arch_validate_flags()") added a late check in mmap_region() to let architectures validate vm_flags. The check needs to happen after calling ->mmap() as the flags can potentially be modified during this callback. If arch_validate_flags() check fails we unmap and free the vma. However, the error path fails to undo the ->mmap() call that previously succeeded and depending on the specific ->mmap() implementation this translates to reference increments, memory allocations and other operations what will not be cleaned up. There are several places (mainly device drivers) where this is an issue. However, one specific example is bpf_map_mmap() which keeps count of the mappings in map->writecnt. The count is incremented on ->mmap() and then decremented on vm_ops->close(). When arch_validate_flags() fails this count is off since bpf_map_mmap_close() is never called. One can reproduce this issue in arm64 devices with MTE support. Here the vm_flags are checked to only allow VM_MTE if VM_MTE_ALLOWED has been set previously. From userspace then is enough to pass the PROT_MTE flag to mmap() syscall to trigger the arch_validate_flags() failure. The following program reproduces this issue: #include #include #include #include #include int main(void) { union bpf_attr attr = { .map_type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(int), .value_size = sizeof(long long), .max_entries = 256, .map_flags = BPF_F_MMAPABLE, }; int fd; fd = syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr)); mmap(NULL, 4096, PROT_WRITE | PROT_MTE, MAP_SHARED, fd, 0); return 0; } By manually adding some log statements to the vm_ops callbacks we can confirm that when passing PROT_MTE to mmap() the map->writecnt is off upon ->release(): With PROT_MTE flag: root@debian:~# ./bpf-test [ 111.263874] bpf_map_write_active_inc: map=9 writecnt=1 [ 111.288763] bpf_map_release: map=9 writecnt=1 Without PROT_MTE flag: root@debian:~# ./bpf-test [ 157.816912] bpf_map_write_active_inc: map=10 writecnt=1 [ 157.830442] bpf_map_write_active_dec: map=10 writecnt=0 [ 157.832396] bpf_map_release: map=10 writecnt=0 This patch fixes the above issue by calling vm_ops->close() when the arch_validate_flags() check fails, after this we can proceed to unmap and free the vma on the error path. Link: https://lkml.kernel.org/r/20220930003844.1210987-1-cmllamas@google.com Fixes: c462ac288f2c ("mm: Introduce arch_validate_flags()") Signed-off-by: Carlos Llamas Reviewed-by: Catalin Marinas Acked-by: Andrii Nakryiko Reviewed-by: Liam Howlett Cc: Christian Brauner (Microsoft) Cc: Michal Hocko Cc: Suren Baghdasaryan Cc: [5.10+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/hugetlb: fix hugetlb not supporting softdirty tracking

2022-08-31T15:18:17Z

commit f96f7a40874d7c746680c0b9f57cef2262ae551f upstream. Patch series "mm/hugetlb: fix write-fault handling for shared mappings", v2. I observed that hugetlb does not support/expect write-faults in shared mappings that would have to map the R/O-mapped page writable -- and I found two case where we could currently get such faults and would erroneously map an anon page into a shared mapping. Reproducers part of the patches. I propose to backport both fixes to stable trees. The first fix needs a small adjustment. This patch (of 2): Staring at hugetlb_wp(), one might wonder where all the logic for shared mappings is when stumbling over a write-protected page in a shared mapping. In fact, there is none, and so far we thought we could get away with that because e.g., mprotect() should always do the right thing and map all pages directly writable. Looks like we were wrong: -------------------------------------------------------------------------- #include #include #include #include #include #include #include #define HUGETLB_SIZE (2 * 1024 * 1024u) static void clear_softdirty(void) { int fd = open("/proc/self/clear_refs", O_WRONLY); const char *ctrl = "4"; int ret; if (fd < 0) { fprintf(stderr, "open(clear_refs) failed\n"); exit(1); } ret = write(fd, ctrl, strlen(ctrl)); if (ret != strlen(ctrl)) { fprintf(stderr, "write(clear_refs) failed\n"); exit(1); } close(fd); } int main(int argc, char **argv) { char *map; int fd; fd = open("/dev/hugepages/tmp", O_RDWR | O_CREAT); if (!fd) { fprintf(stderr, "open() failed\n"); return -errno; } if (ftruncate(fd, HUGETLB_SIZE)) { fprintf(stderr, "ftruncate() failed\n"); return -errno; } map = mmap(NULL, HUGETLB_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); if (map == MAP_FAILED) { fprintf(stderr, "mmap() failed\n"); return -errno; } *map = 0; if (mprotect(map, HUGETLB_SIZE, PROT_READ)) { fprintf(stderr, "mmprotect() failed\n"); return -errno; } clear_softdirty(); if (mprotect(map, HUGETLB_SIZE, PROT_READ|PROT_WRITE)) { fprintf(stderr, "mmprotect() failed\n"); return -errno; } *map = 0; return 0; } -------------------------------------------------------------------------- Above test fails with SIGBUS when there is only a single free hugetlb page. # echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages # ./test Bus error (core dumped) And worse, with sufficient free hugetlb pages it will map an anonymous page into a shared mapping, for example, messing up accounting during unmap and breaking MAP_SHARED semantics: # echo 2 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages # ./test # cat /proc/meminfo | grep HugePages_ HugePages_Total: 2 HugePages_Free: 1 HugePages_Rsvd: 18446744073709551615 HugePages_Surp: 0 Reason in this particular case is that vma_wants_writenotify() will return "true", removing VM_SHARED in vma_set_page_prot() to map pages write-protected. Let's teach vma_wants_writenotify() that hugetlb does not support softdirty tracking. Link: https://lkml.kernel.org/r/20220811103435.188481-1-david@redhat.com Link: https://lkml.kernel.org/r/20220811103435.188481-2-david@redhat.com Fixes: 64e455079e1b ("mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared") Signed-off-by: David Hildenbrand Reviewed-by: Mike Kravetz Cc: Peter Feiner Cc: Kirill A. Shutemov Cc: Cyrill Gorcunov Cc: Pavel Emelyanov Cc: Jamie Liu Cc: Hugh Dickins Cc: Naoya Horiguchi Cc: Bjorn Helgaas Cc: Muchun Song Cc: Peter Xu Cc: [3.18+] Signed-off-by: Andrew Morton Signed-off-by: David Hildenbrand Signed-off-by: Greg Kroah-Hartman

mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region

2022-08-17T13:15:40Z

[ Upstream commit 7f82f922319ede486540e8746769865b9508d2c2 ] Since the beginning, charged is set to 0 to avoid calling vm_unacct_memory twice because vm_unacct_memory will be called by above unmap_region. But since commit 4f74d2c8e827 ("vm: remove 'nr_accounted' calculations from the unmap_vmas() interfaces"), unmap_region doesn't call vm_unacct_memory anymore. So charged shouldn't be set to 0 now otherwise the calling to paired vm_unacct_memory will be missed and leads to imbalanced account. Link: https://lkml.kernel.org/r/20220618082027.43391-1-linmiaohe@huawei.com Fixes: 4f74d2c8e827 ("vm: remove 'nr_accounted' calculations from the unmap_vmas() interfaces") Signed-off-by: Miaohe Lin Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

Merge tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2022-05-28T18:27:17Z

Pull powerpc updates from Michael Ellerman: - Convert to the generic mmap support (ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT) - Add support for outline-only KASAN with 64-bit Radix MMU (P9 or later) - Increase SIGSTKSZ and MINSIGSTKSZ and add support for AT_MINSIGSTKSZ - Enable the DAWR (Data Address Watchpoint) on POWER9 DD2.3 or later - Drop support for system call instruction emulation - Many other small features and fixes Thanks to Alexey Kardashevskiy, Alistair Popple, Andy Shevchenko, Bagas Sanjaya, Bjorn Helgaas, Bo Liu, Chen Huang, Christophe Leroy, Colin Ian King, Daniel Axtens, Dwaipayan Ray, Fabiano Rosas, Finn Thain, Frank Rowand, Fuqian Huang, Guilherme G. Piccoli, Hangyu Hua, Haowen Bai, Haren Myneni, Hari Bathini, He Ying, Jason Wang, Jiapeng Chong, Jing Yangyang, Joel Stanley, Julia Lawall, Kajol Jain, Kevin Hao, Krzysztof Kozlowski, Laurent Dufour, Lv Ruyi, Madhavan Srinivasan, Magali Lemes, Miaoqian Lin, Minghao Chi, Nathan Chancellor, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Oscar Salvador, Pali Rohár, Paul Mackerras, Peng Wu, Qing Wang, Randy Dunlap, Reza Arbab, Russell Currey, Sohaib Mohamed, Vaibhav Jain, Vasant Hegde, Wang Qing, Wang Wensheng, Xiang wangx, Xiaomeng Tong, Xu Wang, Yang Guang, Yang Li, Ye Bin, YueHaibing, Yu Kuai, Zheng Bin, Zou Wei, and Zucheng Zheng. * tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (200 commits) powerpc/64: Include cache.h directly in paca.h powerpc/64s: Only set HAVE_ARCH_UNMAPPED_AREA when CONFIG_PPC_64S_HASH_MMU is set powerpc/xics: Include missing header powerpc/powernv/pci: Drop VF MPS fixup powerpc/fsl_book3e: Don't set rodata RO too early powerpc/microwatt: Add mmu bits to device tree powerpc/powernv/flash: Check OPAL flash calls exist before using powerpc/powermac: constify device_node in of_irq_parse_oldworld() powerpc/powermac: add missing g5_phy_disable_cpu1() declaration selftests/powerpc/pmu: fix spelling mistake "mis-match" -> "mismatch" powerpc: Enable the DAWR on POWER9 DD2.3 and above powerpc/64s: Add CPU_FTRS_POWER10 to ALWAYS mask powerpc/64s: Add CPU_FTRS_POWER9_DD2_2 to CPU_FTRS_ALWAYS mask powerpc: Fix all occurences of "the the" selftests/powerpc/pmu/ebb: remove fixed_instruction.S powerpc/platforms/83xx: Use of_device_get_match_data() powerpc/eeh: Drop redundant spinlock initialization powerpc/iommu: Add missing of_node_put in iommu_init_early_dart powerpc/pseries/vas: Call misc_deregister if sysfs init fails powerpc/papr_scm: Fix leaking nvdimm_events_map elements ...

mm: mmap: register suitable readonly file vmas for khugepaged

2022-05-19T21:08:50Z

The readonly FS THP relies on khugepaged to collapse THP for suitable vmas. But the behavior is inconsistent for "always" mode (https://lore.kernel.org/linux-mm/00f195d4-d039-3cf2-d3a1-a2c88de397a0@suse.cz/). The "always" mode means THP allocation should be tried all the time and khugepaged should try to collapse THP all the time. Of course the allocation and collapse may fail due to other factors and conditions. Currently file THP may not be collapsed by khugepaged even though all the conditions are met. That does break the semantics of "always" mode. So make sure readonly FS vmas are registered to khugepaged to fix the break. Register suitable vmas in common mmap path, that could cover both readonly FS vmas and shmem vmas, so remove the khugepaged calls in shmem.c. Still need to keep the khugepaged call in vma_merge() since vma_merge() is called in a lot of places, for example, madvise, mprotect, etc. Link: https://lkml.kernel.org/r/20220510203222.24246-9-shy828301@gmail.com Signed-off-by: Yang Shi Reported-by: Vlastimil Babka Acked-by: Vlastmil Babka Cc: Kirill A. Shutemov Cc: Miaohe Lin Cc: Song Liu Cc: Rik van Riel Cc: Matthew Wilcox (Oracle) Cc: Zi Yan Cc: Theodore Ts'o Cc: Song Liu Signed-off-by: Andrew Morton

mm: khugepaged: introduce khugepaged_enter_vma() helper

2022-05-19T21:08:50Z

The khugepaged_enter_vma_merge() actually does as the same thing as the khugepaged_enter() section called by shmem_mmap(), so consolidate them into one helper and rename it to khugepaged_enter_vma(). Link: https://lkml.kernel.org/r/20220510203222.24246-8-shy828301@gmail.com Signed-off-by: Yang Shi Acked-by: Vlastmil Babka Cc: Kirill A. Shutemov Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Rik van Riel Cc: Song Liu Cc: Song Liu Cc: Theodore Ts'o Cc: Zi Yan Signed-off-by: Andrew Morton

mmap locking API: fix missed mmap_sem references in comments

2022-05-13T14:20:07Z

Commit c1e8d7c6a7a6 ("mmap locking API: convert mmap_sem comments") missed replacing some references of mmap_sem by mmap_lock due to misspelling (mm_sem instead of mmap_sem). Link: https://lkml.kernel.org/r/20220503113333.214124-1-mail@florommel.de Signed-off-by: Florian Rommel Signed-off-by: Andrew Morton

mm: Add len and flags parameters to arch_get_mmap_end()

2022-05-05T12:11:57Z

Powerpc needs flags and len to make decision on arch_get_mmap_end(). So add them as parameters to arch_get_mmap_end(). Signed-off-by: Christophe Leroy Acked-by: Catalin Marinas Acked-by: Andrew Morton Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/b556daabe7d2bdb2361c4d6130280da7c1ba2c14.1649523076.git.christophe.leroy@csgroup.eu

mm, hugetlbfs: Allow an arch to always use generic versions of get_unmapped_area functions

2022-05-05T12:11:57Z

Unlike most architectures, powerpc can only define at runtime if it is going to use the generic arch_get_unmapped_area() or not. Today, powerpc has a copy of the generic arch_get_unmapped_area() because when selection HAVE_ARCH_UNMAPPED_AREA the generic arch_get_unmapped_area() is not available. Rename it generic_get_unmapped_area() and make it independent of HAVE_ARCH_UNMAPPED_AREA. Do the same for arch_get_unmapped_area_topdown() versus HAVE_ARCH_UNMAPPED_AREA_TOPDOWN. Do the same for hugetlb_get_unmapped_area() versus HAVE_ARCH_HUGETLB_UNMAPPED_AREA. Signed-off-by: Christophe Leroy Reviewed-by: Nicholas Piggin Acked-by: Andrew Morton Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/77f9d3e592f1c8511df9381aa1c4e754651da4d1.1649523076.git.christophe.leroy@csgroup.eu

mm/mmap: drop arch_vm_get_page_pgprot()

2022-04-29T06:16:14Z

There are no platforms left which use arch_vm_get_page_prot(). Just drop generic arch_vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-8-anshuman.khandual@arm.com Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Christophe Leroy Reviewed-by: Catalin Marinas Signed-off-by: Anshuman Khandual Cc: Christoph Hellwig Cc: David S. Miller Cc: Ingo Molnar Cc: Khalid Aziz Cc: Michael Ellerman Cc: Paul Mackerras Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton