CVE-2026-89496

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: always run deallocs on copy-on-write completion

Local fuzzing of 6.12.94 has found the following memory leak
caused by doing 'copy_file_range()' within the same filesystem:

unreferenced object 0xffff88812192c980 (size 32):
  comm "syz.0.49", pid 12095, jiffies 4294964143
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00  ................
    c0 c5 92 21 81 88 ff ff 00 02 00 00 00 06 00 00  ...!............
  backtrace (crc 7068d63f):
    kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
    slab_post_alloc_hook mm/slub.c:4152 [inline]
    slab_alloc_node mm/slub.c:4197 [inline]
    __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358
    kmalloc_noprof include/linux/slab.h:878 [inline]
    ocfs2_find_per_slot_free_list fs/ocfs2/alloc.c:6618 [inline]
    ocfs2_cache_block_dealloc+0x155/0x4b0 fs/ocfs2/alloc.c:6786
    ocfs2_cache_extent_block_free fs/ocfs2/alloc.c:6819 [inline]
    ocfs2_unlink_path+0x286/0x450 fs/ocfs2/alloc.c:2613
    ocfs2_rotate_subtree_left fs/ocfs2/alloc.c:2779 [inline]
    __ocfs2_rotate_tree_left+0x1f6f/0x2da0 fs/ocfs2/alloc.c:2985
    ocfs2_rotate_tree_left+0x283/0xe00 fs/ocfs2/alloc.c:3237
    ocfs2_try_to_merge_extent+0xf56/0x1a20 fs/ocfs2/alloc.c:3825
    ocfs2_split_extent+0x15f4/0x2940 fs/ocfs2/alloc.c:5138
    ocfs2_clear_ext_refcount+0x2f6/0x550 fs/ocfs2/refcounttree.c:3098
    ocfs2_replace_clusters fs/ocfs2/refcounttree.c:3131 [inline]
    ocfs2_make_clusters_writable fs/ocfs2/refcounttree.c:3255 [inline]
    ocfs2_replace_cow+0x991/0x1660 fs/ocfs2/refcounttree.c:3349
    ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3427 [inline]
    ocfs2_refcount_cow+0x5e1/0x9f0 fs/ocfs2/refcounttree.c:3470
    ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2340 [inline]
    ocfs2_file_write_iter+0xbda/0x1880 fs/ocfs2/file.c:2451
    iter_file_splice_write+0x890/0xf60 fs/splice.c:743
    do_splice_from fs/splice.c:944 [inline]
    direct_splice_actor+0x232/0x480 fs/splice.c:1167
    splice_direct_to_actor+0x4b4/0xb60 fs/splice.c:1111
    do_splice_direct_actor fs/splice.c:1210 [inline]
    do_splice_direct+0x10f/0x1c0 fs/splice.c:1236
    do_sendfile+0x430/0xbf0 fs/read_write.c:1388

unreferenced object 0xffff88812192c5c0 (size 32):
  comm "syz.0.49", pid 12095, jiffies 4294964143
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    29 70 00 00 00 00 00 00 19 00 00 00 00 00 00 00  )p..............
  backtrace (crc afec850f):
    kmemleak_alloc_recursive include/linux/kmemleak.h:42 [inline]
    slab_post_alloc_hook mm/slub.c:4152 [inline]
    slab_alloc_node mm/slub.c:4197 [inline]
    __kmalloc_cache_noprof+0x168/0x2c0 mm/slub.c:4358
    kmalloc_noprof include/linux/slab.h:878 [inline]
    kzalloc_noprof include/linux/slab.h:1014 [inline]
    ocfs2_cache_block_dealloc+0x25c/0x4b0 fs/ocfs2/alloc.c:6793
    ocfs2_cache_extent_block_free fs/ocfs2/alloc.c:6819 [inline]
    ocfs2_unlink_path+0x286/0x450 fs/ocfs2/alloc.c:2613
    ocfs2_rotate_subtree_left fs/ocfs2/alloc.c:2779 [inline]
    __ocfs2_rotate_tree_left+0x1f6f/0x2da0 fs/ocfs2/alloc.c:2985
    ocfs2_rotate_tree_left+0x283/0xe00 fs/ocfs2/alloc.c:3237
    ocfs2_try_to_merge_extent+0xf56/0x1a20 fs/ocfs2/alloc.c:3825
    ocfs2_split_extent+0x15f4/0x2940 fs/ocfs2/alloc.c:5138
    ocfs2_clear_ext_refcount+0x2f6/0x550 fs/ocfs2/refcounttree.c:3098
    ocfs2_replace_clusters fs/ocfs2/refcounttree.c:3131 [inline]
    ocfs2_make_clusters_writable fs/ocfs2/refcounttree.c:3255 [inline]
    ocfs2_replace_cow+0x991/0x1660 fs/ocfs2/refcounttree.c:3349
    ocfs2_refcount_cow_hunk fs/ocfs2/refcounttree.c:3427 [inline]
    ocfs2_refcount_cow+0x5e1/0x9f0 fs/ocfs2/refcounttree.c:3470
    ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2340 [inline]
    ocfs2_file_write_iter+0xbda/0x1880 fs/ocfs2/file.c:2451
    iter_file_splice_write+0x890/0xf60 fs/splice.c:743
    do_splice_from fs/splice.c:9
---truncated---