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Joel Fernandes 6de9ee2f30 staging: android: ashmem: Fix lockdep issue during llseek ... commit cb57469c95 upstream. ashmem_mutex create a chain of dependencies like so: (1) mmap syscall -> mmap_sem -> (acquired) ashmem_mmap ashmem_mutex (try to acquire) (block) (2) llseek syscall -> ashmem_llseek -> ashmem_mutex -> (acquired) inode_lock -> inode->i_rwsem (try to acquire) (block) (3) getdents -> iterate_dir -> inode_lock -> inode->i_rwsem (acquired) copy_to_user -> mmap_sem (try to acquire) There is a lock ordering created between mmap_sem and inode->i_rwsem causing a lockdep splat [2] during a syzcaller test, this patch fixes the issue by unlocking the mutex earlier. Functionally that's Ok since we don't need to protect vfs_llseek. [1] https://patchwork.kernel.org/patch/10185031/ [2] https://lkml.org/lkml/2018/1/10/48 Acked-by: Todd Kjos <tkjos@google.com> Cc: Arve Hjonnevag <arve@android.com> Cc: stable@vger.kernel.org Reported-by: syzbot+8ec30bb7bf1a981a2012@syzkaller.appspotmail.com Signed-off-by: Joel Fernandes <joelaf@google.com> Acked-by: Greg Hackmann <ghackmann@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		History 2018-03-19 08:42:45 +01:00
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ion	staging: ion: Fix ion_cma_heap allocations	2018-03-03 10:24:26 +01:00
uapi	staging: android: uapi: drop definitions of removed ION_IOC_{FREE,SHARE} ioctls	2017-06-03 17:38:26 +09:00
ashmem.c	staging: android: ashmem: Fix lockdep issue during llseek	2018-03-19 08:42:45 +01:00
ashmem.h	staging: android: Split uapi out of ashmem.h	2014-02-18 11:03:28 -08:00
Kconfig	staging, android: remove lowmemory killer from the tree	2017-03-09 13:47:03 +01:00
Makefile	staging, android: remove lowmemory killer from the tree	2017-03-09 13:47:03 +01:00
TODO	staging/android: Update Ion TODO list	2017-04-18 20:43:14 +02:00