CVE-2024-49934
Publication date:
21/10/2024
In the Linux kernel, the following vulnerability has been resolved:<br />
<br />
fs/inode: Prevent dump_mapping() accessing invalid dentry.d_name.name<br />
<br />
It&#39;s observed that a crash occurs during hot-remove a memory device,<br />
in which user is accessing the hugetlb. See calltrace as following:<br />
<br />
------------[ cut here ]------------<br />
WARNING: CPU: 1 PID: 14045 at arch/x86/mm/fault.c:1278 do_user_addr_fault+0x2a0/0x790<br />
Modules linked in: kmem device_dax cxl_mem cxl_pmem cxl_port cxl_pci dax_hmem dax_pmem nd_pmem cxl_acpi nd_btt cxl_core crc32c_intel nvme virtiofs fuse nvme_core nfit libnvdimm dm_multipath scsi_dh_rdac scsi_dh_emc s<br />
mirror dm_region_hash dm_log dm_mod<br />
CPU: 1 PID: 14045 Comm: daxctl Not tainted 6.10.0-rc2-lizhijian+ #492<br />
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014<br />
RIP: 0010:do_user_addr_fault+0x2a0/0x790<br />
Code: 48 8b 00 a8 04 0f 84 b5 fe ff ff e9 1c ff ff ff 4c 89 e9 4c 89 e2 be 01 00 00 00 bf 02 00 00 00 e8 b5 ef 24 00 e9 42 fe ff ff 0b 48 83 c4 08 4c 89 ea 48 89 ee 4c 89 e7 5b 5d 41 5c 41 5d 41<br />
RSP: 0000:ffffc90000a575f0 EFLAGS: 00010046<br />
RAX: ffff88800c303600 RBX: 0000000000000000 RCX: 0000000000000000<br />
RDX: 0000000000001000 RSI: ffffffff82504162 RDI: ffffffff824b2c36<br />
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000<br />
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000a57658<br />
R13: 0000000000001000 R14: ffff88800bc2e040 R15: 0000000000000000<br />
FS: 00007f51cb57d880(0000) GS:ffff88807fd00000(0000) knlGS:0000000000000000<br />
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br />
CR2: 0000000000001000 CR3: 00000000072e2004 CR4: 00000000001706f0<br />
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000<br />
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400<br />
Call Trace:<br />
<br />
? __warn+0x8d/0x190<br />
? do_user_addr_fault+0x2a0/0x790<br />
? report_bug+0x1c3/0x1d0<br />
? handle_bug+0x3c/0x70<br />
? exc_invalid_op+0x14/0x70<br />
? asm_exc_invalid_op+0x16/0x20<br />
? do_user_addr_fault+0x2a0/0x790<br />
? exc_page_fault+0x31/0x200<br />
exc_page_fault+0x68/0x200<br />
<br />
BUG: unable to handle page fault for address: 0000000000001000<br />
#PF: supervisor read access in kernel mode<br />
#PF: error_code(0x0000) - not-present page<br />
PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0<br />
Oops: Oops: 0000 [#1] PREEMPT SMP PTI<br />
---[ end trace 0000000000000000 ]---<br />
BUG: unable to handle page fault for address: 0000000000001000<br />
#PF: supervisor read access in kernel mode<br />
#PF: error_code(0x0000) - not-present page<br />
PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0<br />
Oops: Oops: 0000 [#1] PREEMPT SMP PTI<br />
CPU: 1 PID: 14045 Comm: daxctl Kdump: loaded Tainted: G W 6.10.0-rc2-lizhijian+ #492<br />
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014<br />
RIP: 0010:dentry_name+0x1f4/0x440<br />
<br />
? dentry_name+0x2fa/0x440<br />
vsnprintf+0x1f3/0x4f0<br />
vprintk_store+0x23a/0x540<br />
vprintk_emit+0x6d/0x330<br />
_printk+0x58/0x80<br />
dump_mapping+0x10b/0x1a0<br />
? __pfx_free_object_rcu+0x10/0x10<br />
__dump_page+0x26b/0x3e0<br />
? vprintk_emit+0xe0/0x330<br />
? _printk+0x58/0x80<br />
? dump_page+0x17/0x50<br />
dump_page+0x17/0x50<br />
do_migrate_range+0x2f7/0x7f0<br />
? do_migrate_range+0x42/0x7f0<br />
? offline_pages+0x2f4/0x8c0<br />
offline_pages+0x60a/0x8c0<br />
memory_subsys_offline+0x9f/0x1c0<br />
? lockdep_hardirqs_on+0x77/0x100<br />
? _raw_spin_unlock_irqrestore+0x38/0x60<br />
device_offline+0xe3/0x110<br />
state_store+0x6e/0xc0<br />
kernfs_fop_write_iter+0x143/0x200<br />
vfs_write+0x39f/0x560<br />
ksys_write+0x65/0xf0<br />
do_syscall_64+0x62/0x130<br />
<br />
Previously, some sanity check have been done in dump_mapping() before<br />
the print facility parsing &#39;%pd&#39; though, it&#39;s still possible to run into<br />
an invalid dentry.d_name.name.<br />
<br />
Since dump_mapping() only needs to dump the filename only, retrieve it<br />
by itself in a safer way to prevent an unnecessary crash.<br />
<br />
Note that either retrieving the filename with &#39;%pd&#39; or<br />
strncpy_from_kernel_nofault(), the filename could be unreliable.
Severity CVSS v4.0: Pending analysis
Last modification:
03/11/2025