> On Jan 14, 2024, at 5:14 AM, syzbot <syzbot+09b349b3066c2e0b1e96@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 861deac3b092 Linux 6.7-rc7 > git tree: upstream > console+strace: https://syzkaller.appspot.com/x/log.txt?x=155d9131e80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=e0c7078a6b901aa3 > dashboard link: https://syzkaller.appspot.com/bug?extid=09b349b3066c2e0b1e96 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16cefdc9e80000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164fe7e9e80000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/0ea60ee8ed32/disk-861deac3.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/6d69fdc33021/vmlinux-861deac3.xz > kernel image: https://storage.googleapis.com/syzbot-assets/f0158750d452/bzImage-861deac3.xz > mounted in repro: https://storage.googleapis.com/syzbot-assets/bb450f076a10/mount_0.gz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+09b349b3066c2e0b1e96@xxxxxxxxxxxxxxxxxxxxxxxxx > > option from the mount to silence this warning. > ======================================================= > ===================================================== > 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 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x63/0x6b > > 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 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x63/0x6b > > Bytes 18-19 of 20 are uninitialized > Memory access of size 20 starts at ffff888128a46380 > Data copied to user address 0000000020000240 > > CPU: 0 PID: 5006 Comm: syz-executor975 Not tainted 6.7.0-rc7-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 > ===================================================== Hi Amir- The kmalloc() at fs/fhandle.c:39 could be made a kzalloc(). But I wonder if those uninitialized bytes in the file_handle buffer are actually a logic bug in do_sys_name_to_handle(). -- Chuck Lever
