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hugetlbfs: initialize shared policy as part of inode allocation
[ Upstream commit 4742a35 ] 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+ torvalds#364 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: 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 <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Mike Kravetz <[email protected]> Reported-by: Dmitry Vyukov <[email protected]> Acked-by: Hillf Danton <[email protected]> Cc: Tetsuo Handa <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Dave Hansen <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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