CVE-2025-38221

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ext4: fix out of bounds punch offset<br /> <br /> Punching a hole with a start offset that exceeds max_end is not<br /> permitted and will result in a negative length in the<br /> truncate_inode_partial_folio() function while truncating the page cache,<br /> potentially leading to undesirable consequences.<br /> <br /> A simple reproducer:<br /> <br /> truncate -s 9895604649994 /mnt/foo<br /> xfs_io -c "pwrite 8796093022208 4096" /mnt/foo<br /> xfs_io -c "fpunch 8796093022213 25769803777" /mnt/foo<br /> <br /> kernel BUG at include/linux/highmem.h:275!<br /> Oops: invalid opcode: 0000 [#1] SMP PTI<br /> CPU: 3 UID: 0 PID: 710 Comm: xfs_io Not tainted 6.15.0-rc3<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014<br /> RIP: 0010:zero_user_segments.constprop.0+0xd7/0x110<br /> RSP: 0018:ffffc90001cf3b38 EFLAGS: 00010287<br /> RAX: 0000000000000005 RBX: ffffea0001485e40 RCX: 0000000000001000<br /> RDX: 000000000040b000 RSI: 0000000000000005 RDI: 000000000040b000<br /> RBP: 000000000040affb R08: ffff888000000000 R09: ffffea0000000000<br /> R10: 0000000000000003 R11: 00000000fffc7fc5 R12: 0000000000000005<br /> R13: 000000000040affb R14: ffffea0001485e40 R15: ffff888031cd3000<br /> FS: 00007f4f63d0b780(0000) GS:ffff8880d337d000(0000)<br /> knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 000000001ae0b038 CR3: 00000000536aa000 CR4: 00000000000006f0<br /> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000<br /> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400<br /> Call Trace:<br /> <br /> truncate_inode_partial_folio+0x3dd/0x620<br /> truncate_inode_pages_range+0x226/0x720<br /> ? bdev_getblk+0x52/0x3e0<br /> ? ext4_get_group_desc+0x78/0x150<br /> ? crc32c_arch+0xfd/0x180<br /> ? __ext4_get_inode_loc+0x18c/0x840<br /> ? ext4_inode_csum+0x117/0x160<br /> ? jbd2_journal_dirty_metadata+0x61/0x390<br /> ? __ext4_handle_dirty_metadata+0xa0/0x2b0<br /> ? kmem_cache_free+0x90/0x5a0<br /> ? jbd2_journal_stop+0x1d5/0x550<br /> ? __ext4_journal_stop+0x49/0x100<br /> truncate_pagecache_range+0x50/0x80<br /> ext4_truncate_page_cache_block_range+0x57/0x3a0<br /> ext4_punch_hole+0x1fe/0x670<br /> ext4_fallocate+0x792/0x17d0<br /> ? __count_memcg_events+0x175/0x2a0<br /> vfs_fallocate+0x121/0x560<br /> ksys_fallocate+0x51/0xc0<br /> __x64_sys_fallocate+0x24/0x40<br /> x64_sys_call+0x18d2/0x4170<br /> do_syscall_64+0xa7/0x220<br /> entry_SYSCALL_64_after_hwframe+0x76/0x7e<br /> <br /> Fix this by filtering out cases where the punching start offset exceeds<br /> max_end.