Medium · published April 17, 2024
In the Linux kernel, the following vulnerability has been resolved:
do_sys_name_to_handle(): use kzalloc() to fix kernel-infoleak
syzbot identified a kernel information leak vulnerability in
do_sys_name_to_handle() and issued the following report [1].
[1]
"BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x100 lib/usercopy.c:40
instrument_copy_to_user include/linux/instrumented.h:114 [inline]
_copy_to_user+0xbc/0x100 lib/usercopy.c:40
copy_to_user include/linux/uaccess.h:191 [inline]
do_sys_name_to_handle fs/fhandle.c:73 [inline]
__do_sys_name_to_handle_at fs/fhandle.c:112 [inline]
__se_sys_name_to_handle_at+0x949/0xb10 fs/fhandle.c:94
__x64_sys_name_to_handle_at+0xe4/0x140 fs/fhandle.c:94
...
Uninit was created at:
slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
slab_alloc_node mm/slub.c:3478 [inline]
__kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0x121/0x3c0 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
do_sys_name_to_handle fs/fhandle.c:39 [inline]
__do_sys_name_to_handle_at fs/fhandle.c:112 [inline]
__se_sys_name_to_handle_at+0x441/0xb10 fs/fhandle.c:94
__x64_sys_name_to_handle_at+0xe4/0x140 fs/fhandle.c:94
...
Bytes 18-19 of 20 are uninitialized
Memory access of size 20 starts at ffff888128a46380
Data copied to user address 0000000020000240"
Per Chuck Lever's suggestion, use kzalloc() instead of kmalloc() to
solve the problem.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 2.6.39, < 4.19.311 | 4.19.311 |
| linux/linux_kernel | ≥ 4.20, < 5.4.273 | 5.4.273 |
| linux/linux_kernel | ≥ 5.5, < 5.10.214 | 5.10.214 |
| linux/linux_kernel | ≥ 5.11, < 5.15.153 | 5.15.153 |
| linux/linux_kernel | ≥ 5.16, < 6.1.83 | 6.1.83 |
| linux/linux_kernel | ≥ 6.2, < 6.6.23 | 6.6.23 |
| linux/linux_kernel | ≥ 6.7, < 6.7.11 | 6.7.11 |
| linux/linux_kernel | ≥ 6.8, < 6.8.2 | 6.8.2 |