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| author |   Li Nan <linan122@huawei.com> | 2025-08-27 15:39:54 +0800 |
|---|---|---|
| committer |   Ard Biesheuvel <ardb@kernel.org> | 2025-08-28 08:39:49 +0200 |
| commit | a6358f8cf64850f3f27857b8ed8c1b08cfc4685c (patch) | |
| tree | 45e7f8d3fb6539bcb04f5b078eb1a3e5757b909a | |
| parent | efi: stmm: Drop unneeded null pointer check (diff) | |
| download | wireguard-linux-a6358f8cf64850f3f27857b8ed8c1b08cfc4685c.tar.xz wireguard-linux-a6358f8cf64850f3f27857b8ed8c1b08cfc4685c.zip | |
efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare
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: da27a24383b2 ("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>
| -rw-r--r-- | fs/efivarfs/super.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index c4a139911356..4bb4002e3cdf 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -152,6 +152,10 @@ static int efivarfs_d_compare(const struct dentry *dentry, { int guid = len - EFI_VARIABLE_GUID_LEN; + /* Parallel lookups may produce a temporary invalid filename */ + if (guid <= 0) + return 1; + if (name->len != len) return 1; |