In the Linux kernel, the following vulnerability has been resolved:
dosysnametohandle(): use kzalloc() to fix kernel-infoleak
syzbot identified a kernel information leak vulnerability in dosysnametohandle() and issued the following report [1].
[1] "BUG: KMSAN: kernel-infoleak in instrumentcopytouser include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak in _copytouser+0xbc/0x100 lib/usercopy.c:40 instrumentcopytouser include/linux/instrumented.h:114 [inline] copytouser+0xbc/0x100 lib/usercopy.c:40 copytouser include/linux/uaccess.h:191 [inline] dosysnametohandle fs/fhandle.c:73 [inline] _dosysnametohandleat fs/fhandle.c:112 [inline] _sesysnametohandleat+0x949/0xb10 fs/fhandle.c:94 _x64sysnametohandle_at+0xe4/0x140 fs/fhandle.c:94 ...
Uninit was created at: slabpostallochook+0x129/0xa70 mm/slab.h:768 slaballocnode mm/slub.c:3478 [inline] _kmemcacheallocnode+0x5c9/0x970 mm/slub.c:3517 _dokmallocnode mm/slabcommon.c:1006 [inline] _kmalloc+0x121/0x3c0 mm/slabcommon.c:1020 kmalloc include/linux/slab.h:604 [inline] dosysnametohandle fs/fhandle.c:39 [inline] _dosysnametohandleat fs/fhandle.c:112 [inline] _sesysnametohandleat+0x441/0xb10 fs/fhandle.c:94 _x64sysnametohandle_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.