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Eric W. Biederman 0258b5fd7c coredump: Limit coredumps to a single thread group 
Today when a signal is delivered with a handler of SIG_DFL whose
default behavior is to generate a core dump not only that process but
every process that shares the mm is killed.

In the case of vfork this looks like a real world problem.  Consider
the following well defined sequence.

	if (vfork() == 0) {
		execve(...);
		_exit(EXIT_FAILURE);
	}

If a signal that generates a core dump is received after vfork but
before the execve changes the mm the process that called vfork will
also be killed (as the mm is shared).

Similarly if the execve fails after the point of no return the kernel
delivers SIGSEGV which will kill both the exec'ing process and because
the mm is shared the process that called vfork as well.

As far as I can tell this behavior is a violation of people's
reasonable expectations, POSIX, and is unnecessarily fragile when the
system is low on memory.

Solve this by making a userspace visible change to only kill a single
process/thread group.  This is possible because Jann Horn recently
modified[1] the coredump code so that the mm can safely be modified
while the coredump is happening.  With LinuxThreads long gone I don't
expect anyone to have a notice this behavior change in practice.

To accomplish this move the core_state pointer from mm_struct to
signal_struct, which allows different thread groups to coredump
simultatenously.

In zap_threads remove the work to kill anything except for the current
thread group.

v2: Remove core_state from the VM_BUG_ON_MM print to fix
    compile failure when CONFIG_DEBUG_VM is enabled.
    Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>

[1] a07279c9a8 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Link: https://lkml.kernel.org/r/87y27mvnke.fsf@disp2133
Link: https://lkml.kernel.org/r/20211007144701.67592574@canb.auug.org.au
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2021-10-08 12:06:02 -05:00
..
damon mm/damon: add kunit tests 2021-09-08 11:50:25 -07:00
kasan Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
kfence Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
backing-dev.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
balloon_compaction.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
bootmem_info.c mm/bootmem_info.c: mark __init on register_page_bootmem_info_section 2021-09-03 09:58:14 -07:00
cleancache.c
cma.c mm: use proper type for cma_[alloc|release] 2021-05-05 11:27:24 -07:00
cma.h mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
cma_debug.c mm/cma: change cma mutex to irq safe spinlock 2021-05-05 11:27:21 -07:00
cma_sysfs.c mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
compaction.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
debug.c coredump: Limit coredumps to a single thread group 2021-10-08 12:06:02 -05:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: fix corrupted page flag 2021-09-03 09:58:10 -07:00
dmapool.c mm/dmapool: use DEVICE_ATTR_RO macro 2021-06-29 10:53:52 -07:00
early_ioremap.c mm/early_ioremap.c: remove redundant early_ioremap_shutdown() 2021-09-08 11:50:24 -07:00
fadvise.c
failslab.c
filemap.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
frontswap.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
gup.c Revert "mm/gup: remove try_get_page(), call try_get_compound_head() directly" 2021-09-07 11:03:45 -07:00
gup_test.c selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages 2021-05-05 11:27:26 -07:00
gup_test.h selftests/vm: gup_test: fix test flag 2021-05-05 11:27:26 -07:00
highmem.c mm: in_irq() cleanup 2021-09-08 11:50:24 -07:00
hmm.c mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled 2021-09-08 18:45:52 -07:00
huge_memory.c mm,do_huge_pmd_numa_page: remove unnecessary TLB flushing code 2021-09-03 09:58:13 -07:00
hugetlb.c mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY 2021-09-03 09:58:17 -07:00
hugetlb_cgroup.c hugetlb: make free_huge_page irq safe 2021-05-05 11:27:22 -07:00
hugetlb_vmemmap.c mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON 2021-06-30 20:47:26 -07:00
hugetlb_vmemmap.h mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate 2021-06-30 20:47:25 -07:00
hwpoison-inject.c mm: hwpoison: don't drop slab caches for offlining non-LRU page 2021-09-03 09:58:15 -07:00
init-mm.c mm: add setup_initial_init_mm() helper 2021-07-08 11:48:21 -07:00
internal.h mm/numa: automatically generate node migration order 2021-09-03 09:58:16 -07:00
interval_tree.c mm/interval_tree: add comments to improve code readability 2021-04-30 11:20:38 -07:00
io-mapping.c mm: add a io_mapping_map_user helper 2021-04-30 11:20:39 -07:00
ioremap.c mm: move ioremap_page_range to vmalloc.c 2021-09-08 11:50:24 -07:00
Kconfig mm/idle_page_tracking: make PG_idle reusable 2021-09-08 11:50:24 -07:00
Kconfig.debug
khugepaged.c huge tmpfs: SGP_NOALLOC to stop collapse_file() on race 2021-09-03 09:58:12 -07:00
kmemleak.c mm/kmemleak: allow __GFP_NOLOCKDEP passed to kmemleak's gfp 2021-09-08 18:45:53 -07:00
ksm.c mm: KSM: fix data type 2021-09-03 09:58:18 -07:00
list_lru.c mm: vmscan: consolidate shrinker_maps handling code 2021-05-05 11:27:23 -07:00
maccess.c ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault 2021-08-20 11:39:25 +01:00
madvise.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
Makefile mm: introduce Data Access MONitor (DAMON) 2021-09-08 11:50:24 -07:00
mapping_dirty_helpers.c mm/mapping_dirty_helpers: remove double Note in kerneldoc 2021-07-01 11:06:02 -07:00
memblock.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
memcontrol.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
memfd.c Reimplement RLIMIT_MEMLOCK on top of ucounts 2021-04-30 14:14:02 -05:00
memory-failure.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
memory.c mm: fix the deadlock in finish_fault() 2021-07-23 17:43:28 -07:00
memory_hotplug.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
mempolicy.c Merge branches 'akpm' and 'akpm-hotfixes' (patches from Andrew) 2021-09-08 18:52:05 -07:00
mempool.c kasan: use separate (un)poison implementation for integrated init 2021-06-04 19:32:21 +01:00
memremap.c mm/memory_hotplug: remove nid parameter from arch_remove_memory() 2021-09-08 11:50:23 -07:00
memtest.c
migrate.c compat: remove some compat entry points 2021-09-08 15:32:35 -07:00
mincore.c
mlock.c mm: introduce memfd_secret system call to create "secret" memory areas 2021-07-08 11:48:21 -07:00
mm_init.c include/linux/page-flags-layout.h: cleanups 2021-04-30 11:20:42 -07:00
mmap.c Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux 2021-09-04 11:35:47 -07:00
mmap_lock.c mm: mmap_lock: fix disabling preemption directly 2021-07-23 17:43:28 -07:00
mmu_gather.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
mmu_notifier.c mm/mmu_notifiers: ensure range_end() is paired with range_start() 2021-03-25 09:22:55 -07:00
mmzone.c
mprotect.c mm: device exclusive memory access 2021-07-01 11:06:03 -07:00
mremap.c mm/mremap: fix memory account on do_munmap() failure 2021-09-03 09:58:14 -07:00
msync.c mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start 2021-04-30 11:20:37 -07:00
nommu.c Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux 2021-09-04 11:35:47 -07:00
oom_kill.c coredump: Don't perform any cleanups before dumping core 2021-10-06 11:28:39 -05:00
page-writeback.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
page_alloc.c mm/page_alloc.c: avoid accessing uninitialized pcp page migratetype 2021-09-08 18:45:53 -07:00
page_counter.c mm: page_counter: mitigate consequences of a page_counter underflow 2021-04-30 11:20:38 -07:00
page_ext.c mm/idle_page_tracking: make PG_idle reusable 2021-09-08 11:50:24 -07:00
page_idle.c mm/idle_page_tracking: make PG_idle reusable 2021-09-08 11:50:24 -07:00
page_io.c swap: fix swapfile read/write offset 2021-03-02 17:25:46 -07:00
page_isolation.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
page_owner.c mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE 2021-09-08 11:50:22 -07:00
page_poison.c mm: page_poison: print page info when corruption is caught 2021-04-30 11:20:36 -07:00
page_reporting.c mm/page_reporting: allow driver to specify reporting order 2021-06-29 10:53:47 -07:00
page_reporting.h mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
page_vma_mapped.c mm: device exclusive memory access 2021-07-01 11:06:03 -07:00
pagewalk.c mm: pagewalk: fix walk for hugepage tables 2021-06-29 10:53:49 -07:00
percpu-internal.h Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu 2021-07-01 17:17:24 -07:00
percpu-km.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu-stats.c percpu: rework memcg accounting 2021-06-05 20:43:15 +00:00
percpu-vm.c percpu: flush tlb in pcpu_reclaim_populated() 2021-07-04 18:30:17 +00:00
percpu.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
pgalloc-track.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgtable-generic.c mm/thp: fix __split_huge_pmd_locked() on shmem migration entry 2021-06-16 09:24:42 -07:00
process_vm_access.c mm/process_vm_access.c: remove duplicate include 2021-05-05 11:27:27 -07:00
ptdump.c mm: ptdump: fix build failure 2021-04-16 16:10:37 -07:00
readahead.c mm: Protect operations adding pages to page cache with invalidate_lock 2021-07-13 13:14:27 +02:00
rmap.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
rodata_test.c
secretmem.c mm/secretmem: use refcount_t instead of atomic_t 2021-09-08 11:50:24 -07:00
shmem.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
shuffle.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
shuffle.h mm/shuffle: fix section mismatch warning 2021-05-22 15:09:07 -10:00
slab.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
slab.h mm/memcg: fix NULL pointer dereference in memcg_slab_free_hook() 2021-07-30 10:14:39 -07:00
slab_common.c mm: slub: move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context 2021-09-04 01:12:23 +02:00
slob.c mm: Don't build mm_dump_obj() on CONFIG_PRINTK=n kernels 2021-03-08 14:18:46 -08:00
slub.c mm, slub: convert kmem_cpu_slab protection to local_lock 2021-09-04 10:22:01 +02:00
sparse-vmemmap.c mm: sparsemem: split the huge PMD mapping of vmemmap pages 2021-06-30 20:47:26 -07:00
sparse.c mm: introduce memmap_alloc() to unify memory map allocation 2021-09-03 09:58:15 -07:00
swap.c mm: delete unused get_kernel_page() 2021-09-03 09:58:11 -07:00
swap_cgroup.c
swap_slots.c mm: Replace deprecated CPU-hotplug functions. 2021-08-28 01:46:17 +02:00
swap_state.c Revert "mm: swap: check if swap backing device is congested or not" 2021-08-20 11:31:42 -07:00
swapfile.c mm, memcg: inline swap-related functions to improve disabled memcg config 2021-09-03 09:58:12 -07:00
truncate.c Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
usercopy.c
userfaultfd.c userfaultfd: change mmap_changing to atomic 2021-09-03 09:58:16 -07:00
util.c mm: don't allow oversized kvmalloc() calls 2021-09-02 09:47:01 -07:00
vmacache.c
vmalloc.c Merge branch 'akpm' (patches from Andrew) 2021-09-08 12:55:35 -07:00
vmpressure.c mm/vmpressure: replace vmpressure_to_css() with vmpressure_to_memcg() 2021-09-03 09:58:17 -07:00
vmscan.c mm,vmscan: fix divide by zero in get_scan_count 2021-09-08 18:45:53 -07:00
vmstat.c mm/vmstat: protect per cpu variables with preempt disable on RT 2021-09-08 15:32:34 -07:00
workingset.c mm/workingset: correct kernel-doc notations 2021-09-08 11:50:28 -07:00
z3fold.c mm/z3fold: add kerneldoc fields for z3fold_pool 2021-07-01 11:06:03 -07:00
zbud.c mm/zbud: add kerneldoc fields for zbud_pool 2021-07-01 11:06:03 -07:00
zpool.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
zsmalloc.c mm/zsmalloc.c: improve readability for async_free_zspage() 2021-07-01 11:06:02 -07:00
zswap.c mm/zswap.c: fix two bugs in zswap_writeback_entry() 2021-06-30 20:47:31 -07:00