On Tue, 04 Jan 2022 02:03:17 -0800 syzbot <syzbot+217f792c92599518a2ab@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 81c325bbf94e kmsan: hooks: do not check memory in kmsan_in.. > git tree: https://github.com/google/kmsan.git master > console output: https://syzkaller.appspot.com/x/log.txt?x=112b8f7db00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=2d8b9a11641dc9aa > dashboard link: https://syzkaller.appspot.com/bug?extid=217f792c92599518a2ab > compiler: clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13366ea5b00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14526cb3b00000 Thanks. I don't get it. > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+217f792c92599518a2ab@xxxxxxxxxxxxxxxxxxxxxxxxx > > ===================================================== > BUG: KMSAN: uninit-value in mpol_rebind_policy mm/mempolicy.c:352 [inline] > BUG: KMSAN: uninit-value in mpol_rebind_task+0x2ac/0x2c0 mm/mempolicy.c:368 > mpol_rebind_policy mm/mempolicy.c:352 [inline] Appears to be if (!mpol_store_user_nodemask(pol) && But if so, why didn't it also report mpol_store_user_nodemask mm/mempolicy.c:184 [inline] which is where the return pol->flags & MPOL_MODE_FLAGS; actually happened? > mpol_rebind_task+0x2ac/0x2c0 mm/mempolicy.c:368 > cpuset_change_task_nodemask kernel/cgroup/cpuset.c:1711 [inline] > cpuset_attach+0x787/0x15e0 kernel/cgroup/cpuset.c:2278 > cgroup_migrate_execute+0x1023/0x1d20 kernel/cgroup/cgroup.c:2515 > cgroup_migrate kernel/cgroup/cgroup.c:2771 [inline] > cgroup_attach_task+0x540/0x8b0 kernel/cgroup/cgroup.c:2804 > __cgroup1_procs_write+0x5cc/0x7a0 kernel/cgroup/cgroup-v1.c:520 > cgroup1_tasks_write+0x94/0xb0 kernel/cgroup/cgroup-v1.c:539 > cgroup_file_write+0x4c2/0x9e0 kernel/cgroup/cgroup.c:3852 > kernfs_fop_write_iter+0x66a/0x9f0 fs/kernfs/file.c:296 > call_write_iter include/linux/fs.h:2162 [inline] > new_sync_write fs/read_write.c:503 [inline] > vfs_write+0x1318/0x2030 fs/read_write.c:590 > ksys_write+0x28b/0x510 fs/read_write.c:643 > __do_sys_write fs/read_write.c:655 [inline] > __se_sys_write fs/read_write.c:652 [inline] > __x64_sys_write+0xdb/0x120 fs/read_write.c:652 > do_syscall_x64 arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Uninit was created at: > slab_post_alloc_hook mm/slab.h:524 [inline] > slab_alloc_node mm/slub.c:3251 [inline] > slab_alloc mm/slub.c:3259 [inline] > kmem_cache_alloc+0x902/0x11c0 mm/slub.c:3264 > mpol_new mm/mempolicy.c:293 [inline] But mpol_new() does policy->flags = flags; > do_set_mempolicy+0x421/0xb70 mm/mempolicy.c:853 > kernel_set_mempolicy mm/mempolicy.c:1504 [inline] > __do_sys_set_mempolicy mm/mempolicy.c:1510 [inline] > __se_sys_set_mempolicy+0x44c/0xb60 mm/mempolicy.c:1507 > __x64_sys_set_mempolicy+0xd8/0x110 mm/mempolicy.c:1507 > do_syscall_x64 arch/x86/entry/common.c:51 [inline] > do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > CPU: 1 PID: 3479 Comm: syz-executor124 Not tainted 5.16.0-rc5-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > =====================================================
