kernel/linux.git/ipc/shm.c, branch v6.12.80

ipc: fix to protect IPCS lookups using RCU

2025-06-27T10:11:22+00:00

commit d66adabe91803ef34a8b90613c81267b5ded1472 upstream. syzbot reported that it discovered a use-after-free vulnerability, [0] [0]: https://lore.kernel.org/all/67af13f8.050a0220.21dd3.0038.GAE@google.com/ idr_for_each() is protected by rwsem, but this is not enough. If it is not protected by RCU read-critical region, when idr_for_each() calls radix_tree_node_free() through call_rcu() to free the radix_tree_node structure, the node will be freed immediately, and when reading the next node in radix_tree_for_each_slot(), the already freed memory may be read. Therefore, we need to add code to make sure that idr_for_each() is protected within the RCU read-critical region when we call it in shm_destroy_orphaned(). Link: https://lkml.kernel.org/r/20250424143322.18830-1-aha310510@gmail.com Fixes: b34a6b1da371 ("ipc: introduce shm_rmid_forced sysctl") Signed-off-by: Jeongjun Park Reported-by: syzbot+a2b84e569d06ca3a949c@syzkaller.appspotmail.com Cc: Jeongjun Park Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Vasiliy Kulikov Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

ipc/shm, mm: drop do_vma_munmap()

2024-09-04T04:15:52+00:00

The do_vma_munmap() wrapper existed for callers that didn't have a vma iterator and needed to check the vma mseal status prior to calling the underlying munmap(). All callers now use a vma iterator and since the mseal check has been moved to do_vmi_align_munmap() and the vmas are aligned, this function can just be called instead. do_vmi_align_munmap() can no longer be static as ipc/shm is using it and it is exported via the mm.h header. Link: https://lkml.kernel.org/r/20240830040101.822209-19-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Cc: Bert Karwatzki Cc: Jeff Xu Cc: Jiri Olsa Cc: Kees Cook Cc: Lorenzo Stoakes Cc: Mark Brown Cc: Matthew Wilcox Cc: "Paul E. McKenney" Cc: Paul Moore Cc: Sidhartha Kumar Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

fs: Add FOP_HUGE_PAGES

2024-04-09T08:53:44+00:00

Instead of checking for specific file_operations, add a bit to file_operations which denotes a file that only contain hugetlb pages. This lets us make hugetlbfs_file_operations static, and removes is_file_shm_hugepages() completely. Signed-off-by: Matthew Wilcox (Oracle) Link: https://lore.kernel.org/r/20240407201122.3783877-1-willy@infradead.org Signed-off-by: Christian Brauner

shm: Slim down dependencies

2023-12-21T00:26:31+00:00

list_head is in types.h, not list.h., and the uapi header wasn't needed. Signed-off-by: Kent Overstreet

mempolicy: alloc_pages_mpol() for NUMA policy without vma

2023-10-25T23:47:16+00:00

Shrink shmem's stack usage by eliminating the pseudo-vma from its folio allocation. alloc_pages_mpol(gfp, order, pol, ilx, nid) becomes the principal actor for passing mempolicy choice down to __alloc_pages(), rather than vma_alloc_folio(gfp, order, vma, addr, hugepage). vma_alloc_folio() and alloc_pages() remain, but as wrappers around alloc_pages_mpol(). alloc_pages_bulk_*() untouched, except to provide the additional args to policy_nodemask(), which subsumes policy_node(). Cleanup throughout, cutting out some unhelpful "helpers". It would all be much simpler without MPOL_INTERLEAVE, but that adds a dynamic to the constant mpol: complicated by v3.6 commit 09c231cb8bfd ("tmpfs: distribute interleave better across nodes"), which added ino bias to the interleave, hidden from mm/mempolicy.c until this commit. Hence "ilx" throughout, the "interleave index". Originally I thought it could be done just with nid, but that's wrong: the nodemask may come from the shared policy layer below a shmem vma, or it may come from the task layer above a shmem vma; and without the final nodemask then nodeid cannot be decided. And how ilx is applied depends also on page order. The interleave index is almost always irrelevant unless MPOL_INTERLEAVE: with one exception in alloc_pages_mpol(), where the NO_INTERLEAVE_INDEX passed down from vma-less alloc_pages() is also used as hint not to use THP-style hugepage allocation - to avoid the overhead of a hugepage arg (though I don't understand why we never just added a GFP bit for THP - if it actually needs a different allocation strategy from other pages of the same order). vma_alloc_folio() still carries its hugepage arg here, but it is not used, and should be removed when agreed. get_vma_policy() no longer allows a NULL vma: over time I believe we've eradicated all the places which used to need it e.g. swapoff and madvise used to pass NULL vma to read_swap_cache_async(), but now know the vma. [hughd@google.com: handle NULL mpol being passed to __read_swap_cache_async()] Link: https://lkml.kernel.org/r/ea419956-4751-0102-21f7-9c93cb957892@google.com Link: https://lkml.kernel.org/r/74e34633-6060-f5e3-aee-7040d43f2e93@google.com Link: https://lkml.kernel.org/r/1738368e-bac0-fd11-ed7f-b87142a939fe@google.com Signed-off-by: Hugh Dickins Cc: Andi Kleen Cc: Christoph Lameter Cc: David Hildenbrand Cc: Greg Kroah-Hartman Cc: Huang Ying Cc: Kefeng Wang Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Michal Hocko Cc: Mike Kravetz Cc: Nhat Pham Cc: Sidhartha Kumar Cc: Suren Baghdasaryan Cc: Tejun heo Cc: Vishal Moola (Oracle) Cc: Yang Shi Cc: Yosry Ahmed Cc: Domenico Cerasuolo Cc: Johannes Weiner Signed-off-by: Andrew Morton

mm: Re-introduce vm_flags to do_mmap()

2023-07-11T21:12:18+00:00

There was no more caller passing vm_flags to do_mmap(), and vm_flags was removed from the function's input by: commit 45e55300f114 ("mm: remove unnecessary wrapper function do_mmap_pgoff()"). There is a new user now. Shadow stack allocation passes VM_SHADOW_STACK to do_mmap(). Thus, re-introduce vm_flags to do_mmap(). Co-developed-by: Rick Edgecombe Signed-off-by: Yu-cheng Yu Signed-off-by: Rick Edgecombe Signed-off-by: Dave Hansen Reviewed-by: Borislav Petkov (AMD) Reviewed-by: Peter Collingbourne Reviewed-by: Kees Cook Reviewed-by: Kirill A. Shutemov Reviewed-by: Mark Brown Acked-by: Mike Rapoport (IBM) Acked-by: David Hildenbrand Tested-by: Pengfei Xu Tested-by: John Allen Tested-by: Kees Cook Tested-by: Mark Brown Link: https://lore.kernel.org/all/20230613001108.3040476-5-rick.p.edgecombe%40intel.com

ipc/shm: introduce new do_vma_munmap() to munmap

2023-02-10T00:51:33+00:00

The shm already has the vma iterator in position for a write. do_vmi_munmap() searches for the correct position and aligns the write, so it is not the right function to use in this case. The shm VMA tree modification is similar to the brk munmap situation, the vma iterator is in position and the VMA is already known. This patch generalizes the brk munmap function do_brk_munmap() to be used for any other callers with the vma iterator already in position to munmap a VMA. Link: https://lkml.kernel.org/r/20230126212049.980501-1-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Reported-by: Sven Schnelle Link: https://lore.kernel.org/linux-mm/yt9dh6wec21a.fsf@linux.ibm.com/ Cc: Arnd Bergmann Signed-off-by: Andrew Morton

ipc/shm: use the vma iterator for munmap calls

2023-02-10T00:51:32+00:00

Pass through the vma iterator to do_vmi_munmap() to handle the iterator state internally Link: https://lkml.kernel.org/r/20230120162650.984577-16-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Signed-off-by: Andrew Morton

ipc/shm: call underlying open/close vm_ops

2022-11-23T02:50:42+00:00

Shared memory segments can be created that are backed by hugetlb pages. When this happens, the vmas associated with any mappings (shmat) are marked VM_HUGETLB, yet the vm_ops for such mappings are provided by ipc/shm (shm_vm_ops). There is a mechanism to call the underlying hugetlb vm_ops, and this is done for most operations. However, it is not done for open and close. This was not an issue until the introduction of the hugetlb vma_lock. This lock structure is pointed to by vm_private_data and the open/close vm_ops help maintain this structure. The special hugetlb routine called at fork took care of structure updates at fork time. However, vma_splitting is not properly handled for ipc shared memory mappings backed by hugetlb pages. This can result in a "kernel NULL pointer dereference" BUG or use after free as two vmas point to the same lock structure. Update the shm open and close routines to always call the underlying open and close routines. Link: https://lkml.kernel.org/r/20221114210018.49346-1-mike.kravetz@oracle.com Fixes: 8d9bfb260814 ("hugetlb: add vma based lock for pmd sharing") Signed-off-by: Mike Kravetz Reported-by: Doug Nelson Reported-by: Cc: Alexander Mikhalitsyn Cc: "Eric W . Biederman" Cc: Manfred Spraul Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Michal Hocko Signed-off-by: Andrew Morton

ipc/shm: use VMA iterator instead of linked list

2022-09-27T02:46:21+00:00

The VMA iterator is faster than the linked llist, and it can be walked even when VMAs are being removed from the address space, so there's no need to keep track of 'next'. Link: https://lkml.kernel.org/r/20220906194824.2110408-46-Liam.Howlett@oracle.com Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Liam R. Howlett Tested-by: Yu Zhao Cc: Catalin Marinas Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: SeongJae Park Cc: Sven Schnelle Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton