On March 26, 2017 5:38 AM Mike Kravetz wrote: > > Any time after inode allocation, destroy_inode can be called. The > hugetlbfs inode contains a shared_policy structure, and > mpol_free_shared_policy is unconditionally called as part of > hugetlbfs_destroy_inode. Initialize the policy as part of inode > allocation so that any quick (error path) calls to destroy_inode > will be handed an initialized policy. > > syzkaller fuzzer found this bug, that resulted in the following: > > BUG: KASAN: user-memory-access in atomic_inc > include/asm-generic/atomic-instrumented.h:87 [inline] at addr > 000000131730bd7a > BUG: KASAN: user-memory-access in __lock_acquire+0x21a/0x3a80 > kernel/locking/lockdep.c:3239 at addr 000000131730bd7a > Write of size 4 by task syz-executor6/14086 > CPU: 3 PID: 14086 Comm: syz-executor6 Not tainted 4.11.0-rc3+ #364 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:16 [inline] > dump_stack+0x1b8/0x28d lib/dump_stack.c:52 > kasan_report_error mm/kasan/report.c:291 [inline] > kasan_report.part.2+0x34a/0x480 mm/kasan/report.c:316 > kasan_report+0x21/0x30 mm/kasan/report.c:303 > check_memory_region_inline mm/kasan/kasan.c:326 [inline] > check_memory_region+0x137/0x190 mm/kasan/kasan.c:333 > kasan_check_write+0x14/0x20 mm/kasan/kasan.c:344 > atomic_inc include/asm-generic/atomic-instrumented.h:87 [inline] > __lock_acquire+0x21a/0x3a80 kernel/locking/lockdep.c:3239 > lock_acquire+0x1ee/0x590 kernel/locking/lockdep.c:3762 > __raw_write_lock include/linux/rwlock_api_smp.h:210 [inline] > _raw_write_lock+0x33/0x50 kernel/locking/spinlock.c:295 > mpol_free_shared_policy+0x43/0xb0 mm/mempolicy.c:2536 > hugetlbfs_destroy_inode+0xca/0x120 fs/hugetlbfs/inode.c:952 > alloc_inode+0x10d/0x180 fs/inode.c:216 > new_inode_pseudo+0x69/0x190 fs/inode.c:889 > new_inode+0x1c/0x40 fs/inode.c:918 > hugetlbfs_get_inode+0x40/0x420 fs/hugetlbfs/inode.c:734 > hugetlb_file_setup+0x329/0x9f0 fs/hugetlbfs/inode.c:1282 > newseg+0x422/0xd30 ipc/shm.c:575 > ipcget_new ipc/util.c:285 [inline] > ipcget+0x21e/0x580 ipc/util.c:639 > SYSC_shmget ipc/shm.c:673 [inline] > SyS_shmget+0x158/0x230 ipc/shm.c:657 > entry_SYSCALL_64_fastpath+0x1f/0xc2 > > Analysis provided by Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > v2: Remove now redundant initialization in hugetlbfs_get_root > > Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > --- Acked-by: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
