CVE-2025-40349

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

hfs: validate record offset in hfsplusbmapalloc

hfsplusbmapalloc can trigger a crash if a record offset or length is larger than node_size

[ 15.264282] BUG: KASAN: slab-out-of-bounds in hfsplusbmapalloc+0x887/0x8b0 [ 15.265192] Read of size 8 at addr ffff8881085ca188 by task test/183 [ 15.265949] [ 15.266163] CPU: 0 UID: 0 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] <TASK> [ 15.266169] dumpstacklvl+0x53/0x70 [ 15.266173] printreport+0xd0/0x660 [ 15.266181] kasanreport+0xce/0x100 [ 15.266185] hfsplusbmapalloc+0x887/0x8b0 [ 15.266208] hfsbtreeincheight.isra.0+0xd5/0x7c0 [ 15.266217] hfsplusbrec_insert+0x870/0xb00 [ 15.266222] __hfsplusextwrite_extent+0x428/0x570 [ 15.266225] __hfsplusextcacheextent+0x5e/0x910 [ 15.266227] hfsplusextreadextent+0x1b2/0x200 [ 15.266233] hfsplusfileextend+0x5a7/0x1000 [ 15.266237] hfsplusgetblock+0x12b/0x8c0 [ 15.266238] __blockwritebeginint+0x36b/0x12c0 [ 15.266251] blockwritebegin+0x77/0x110 [ 15.266252] contwritebegin+0x428/0x720 [ 15.266259] hfspluswritebegin+0x51/0x100 [ 15.266262] contwritebegin+0x272/0x720 [ 15.266270] hfspluswritebegin+0x51/0x100 [ 15.266274] genericperformwrite+0x321/0x750 [ 15.266285] genericfilewriteiter+0xc3/0x310 [ 15.266289] _kernelwriteiter+0x2fd/0x800 [ 15.266296] dumpuserrange+0x2ea/0x910 [ 15.266301] elfcoredump+0x2a94/0x2ed0 [ 15.266320] vfscoredump+0x1d85/0x45e0 [ 15.266349] getsignal+0x12e3/0x1990 [ 15.266357] archdosignalorrestart+0x89/0x580 [ 15.266362] irqentryexittousermode+0xab/0x110 [ 15.266364] asmexcpagefault+0x26/0x30 [ 15.266366] RIP: 0033:0x41bd35 [ 15.266367] Code: bc d1 f3 0f 7f 27 f3 0f 7f 6f 10 f3 0f 7f 77 20 f3 0f 7f 7f 30 49 83 c0 0f 49 29 d0 48 8d 7c 17 31 e9 9f 0b 00 00 66 0f ef c0 <f3> 0f 6f 0e f3 0f 6f 56 10 66 0f 74 c1 66 0f d7 d0 49 83 f8f [ 15.266369] RSP: 002b:00007ffc9e62d078 EFLAGS: 00010283 [ 15.266371] RAX: 00007ffc9e62d100 RBX: 0000000000000000 RCX: 0000000000000000 [ 15.266372] RDX: 00000000000000e0 RSI: 0000000000000000 RDI: 00007ffc9e62d100 [ 15.266373] RBP: 0000400000000040 R08: 00000000000000e0 R09: 0000000000000000 [ 15.266374] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 15.266375] R13: 0000000000000000 R14: 0000000000000000 R15: 0000400000000000 [ 15.266376] </TASK>

When calling hfsplusbmapalloc to allocate a free node, this function first retrieves the bitmap from header node and map node using node->page together with the offset and length from hfsbreclenoff

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, if the retrieved offset or length is invalid(i.e. exceeds node_size), the code may end up accessing pages outside the allocated range for this node.

This patch adds proper validation of both offset and length before use, preventing out-of-bounds page access. Move isbnodeoffsetvalid and checkandcorrectrequestedlength to hfsplusfs.h, as they may be required by other functions.