linux-yocto/fs/efivarfs
Li Nan 71581a82f3 efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare
[ Upstream commit a6358f8cf64850f3f27857b8ed8c1b08cfc4685c ]

Observed on kernel 6.6 (present on master as well):

  BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0
  Call trace:
   kasan_check_range+0xe8/0x190
   __asan_loadN+0x1c/0x28
   memcmp+0x98/0xd0
   efivarfs_d_compare+0x68/0xd8
   __d_lookup_rcu_op_compare+0x178/0x218
   __d_lookup_rcu+0x1f8/0x228
   d_alloc_parallel+0x150/0x648
   lookup_open.isra.0+0x5f0/0x8d0
   open_last_lookups+0x264/0x828
   path_openat+0x130/0x3f8
   do_filp_open+0x114/0x248
   do_sys_openat2+0x340/0x3c0
   __arm64_sys_openat+0x120/0x1a0

If dentry->d_name.len < EFI_VARIABLE_GUID_LEN , 'guid' can become
negative, leadings to oob. The issue can be triggered by parallel
lookups using invalid filename:

  T1			T2
  lookup_open
   ->lookup
    simple_lookup
     d_add
     // invalid dentry is added to hash list

			lookup_open
			 d_alloc_parallel
			  __d_lookup_rcu
			   __d_lookup_rcu_op_compare
			    hlist_bl_for_each_entry_rcu
			    // invalid dentry can be retrieved
			     ->d_compare
			      efivarfs_d_compare
			      // oob

Fix it by checking 'guid' before cmp.

Fixes: da27a24383 ("efivarfs: guid part of filenames are case-insensitive")
Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Wu Guanghao <wuguanghao3@huawei.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-09-04 16:55:43 +02:00
..
file.c efivarfs: Revert "allow creation of zero length files" 2025-03-07 12:31:04 +01:00
inode.c Merge branch 'efivarfs' into next 2025-01-19 17:50:58 +01:00
internal.h efivarfs: support freeze/thaw 2025-05-09 12:41:23 +02:00
Kconfig
Makefile efi: vars: Move efivar caching layer into efivarfs 2022-06-24 20:40:19 +02:00
super.c efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare 2025-09-04 16:55:43 +02:00
vars.c efivarfs: add variable resync after hibernation 2025-01-22 13:28:17 +01:00