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Subject[PATCH] xfs: Fix UBSAN null-ptr-deref in xfs_sysfs_init
Date
If xfs_sysfs_init is called with parent_kobj == NULL, UBSAN
shows the following warning:

UBSAN: null-ptr-deref in ./fs/xfs/xfs_sysfs.h:37:23
member access within null pointer of type 'struct xfs_kobj'
Call Trace:
dump_stack+0x10e/0x195
ubsan_type_mismatch_common+0x241/0x280
__ubsan_handle_type_mismatch_v1+0x32/0x40
init_xfs_fs+0x12b/0x28f
do_one_initcall+0xdd/0x1d0
do_initcall_level+0x151/0x1b6
do_initcalls+0x50/0x8f
do_basic_setup+0x29/0x2b
kernel_init_freeable+0x19f/0x20b
kernel_init+0x11/0x1e0
ret_from_fork+0x22/0x30

Fix it by checking parent_kobj before the code accesses its member.

Signed-off-by: Eiichi Tsukata <devel@etsukata.com>
---
fs/xfs/xfs_sysfs.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_sysfs.h b/fs/xfs/xfs_sysfs.h
index e9f810fc6731..aad67dc4ab5b 100644
--- a/fs/xfs/xfs_sysfs.h
+++ b/fs/xfs/xfs_sysfs.h
@@ -32,9 +32,9 @@ xfs_sysfs_init(
struct xfs_kobj *parent_kobj,
const char *name)
{
+ struct kobject *parent = parent_kobj ? &parent_kobj->kobject : NULL;
init_completion(&kobj->complete);
- return kobject_init_and_add(&kobj->kobject, ktype,
- &parent_kobj->kobject, "%s", name);
+ return kobject_init_and_add(&kobj->kobject, ktype, parent, "%s", name);
}

static inline void
--
2.26.2
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