In the Linux kernel, following vulnerability has been resolved: hfs: validate record offset in hfsplus_bmap_alloc hfsplus_bmap_alloc can trigger a crash if a record or length is larger than node_size [ 15.264282] BUG: KASAN: slab-out-of-bounds hfsplus_bmap_alloc+0x887/0x8b0 [ 15.265192] Read of size 8 at addr ffff8881085ca188 by task test/183 [ 15.265949] [ 15.266163] CPU: 0 UID: PID: 183 Comm: test Not tainted 6.17.0-rc2-gc17b750b3ad9 #14 PREEMPT(voluntary) [ 15.266165] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 15.266167] Call Trace: [ 15.266168] [ 15.266169] dump_stack_lvl+0x53/0x70 [ 15.266173] print_report+0xd0/0x660 [ 15.266181] kasan_report+0xce/0x100 [ 15.266185] 15.266208] hfs_btree_inc_height.isra.0+0xd5/0x7c0 [ 15.266217] hfsplus_brec_insert+0x870/0xb00 [ 15.266222] __hfsplus_ext_write_extent+0x428/0x570 [ 15.266225] __hfsplus_ext_cache_extent+0x5e/0x910 [ 15.266227] hfsplus_ext_read_extent+0x1b2/0x200 [ 15.266233] hfsplus_file_extend+0x5a7/0x1000 [ 15.266237] hfsplus_get_block+0x12b/0x8c0 [ 15.266238] __block_write_begin_int+0x36b/0x12c0 [ 15.266251] block_write_begin+0x77/0x110 [ 15.266252] cont_write_begin+0x428/0x720 [ 15.266259] hfsplus_write_begin+0x51/0x100 [ 15.266262] cont_write_begin+0x272/0x720 [ 15.266270] 15.266274] generic_perform_write+0x321/0x750 [ 15.266285] generic_file_write_iter+0xc3/0x310 [ 15.266289] __kernel_write_iter+0x2fd/0x800 [ 15.266296] dump_user_range+0x2ea/0x910 [ 15.266301] elf_core_dump+0x2a94/0x2ed0 [ 15.266320] vfs_coredump+0x1d85/0x45e0 [ 15.266349] get_signal+0x12e3/0x1990 [ 15.266357] arch_do_signal_or_restart+0x89/0x580 [ 15.266362] irqentry_exit_to_user_mode+0xab/0x110 [ 15.266364] asm_exc_page_fault+0x26/0x30 [ 15.266366] RIP: 0033:0x41bd35 [ 15.266367] Code: bc d1 f3 0f 7f 27 6f 10 77 20 30 49 83 c0 29 d0 48 8d 7c 17 31 e9 9f 0b 00 66 ef 0e 56 74 c1 d7 f8f [ 15.266369] RSP: 002b:00007ffc9e62d078 EFLAGS: 00010283 [ 15.266371] RAX: 00007ffc9e62d100 RBX: 0000000000000000 RCX: 0000000000000000 [ 15.266372] RDX: 00000000000000e0 RSI: RDI: 00007ffc9e62d100 [ 15.266373] RBP: 0000400000000040 R08: R09: 15.266374] R10: R11: 0000000000000246 R12: 15.266375] R13: R14: R15: 0000400000000000 [ 15.266376] When calling hfsplus_bmap_alloc to allocate free node, this function first retrieves bitmap from header node and map using node->page together with hfs_brec_lenoff ``` len = hfs_brec_lenoff(node, 2, &off16); off off16; off += node->page_offset; pagep node->page (off >> PAGE_SHIFT); data kmap_local_page(*pagep); ``` However, retrieved invalid(i.e. exceeds node_size), code may end up accessing pages outside allocated range for node. This patch adds proper validation both before use, preventing out-of-bounds page access. Move is_bnode_offset_valid and check_and_correct_requested_length hfsplus_fs.h, as they be required other functions.