user/sven/linux.git/ipc, branch v3.11.10

ipc,shm: fix shm_file deletion races

2013-11-29T18:42:15Z

commit a399b29dfbaaaf91162b2dc5a5875dd51bbfa2a1 upstream. When IPC_RMID races with other shm operations there's potential for use-after-free of the shm object's associated file (shm_file). Here's the race before this patch: TASK 1 TASK 2 ------ ------ shm_rmid() ipc_lock_object() shmctl() shp = shm_obtain_object_check() shm_destroy() shum_unlock() fput(shp->shm_file) ipc_lock_object() shmem_lock(shp->shm_file) The oops is caused because shm_destroy() calls fput() after dropping the ipc_lock. fput() clears the file's f_inode, f_path.dentry, and f_path.mnt, which causes various NULL pointer references in task 2. I reliably see the oops in task 2 if with shmlock, shmu This patch fixes the races by: 1) set shm_file=NULL in shm_destroy() while holding ipc_object_lock(). 2) modify at risk operations to check shm_file while holding ipc_object_lock(). Example workloads, which each trigger oops... Workload 1: while true; do id=$(shmget 1 4096) shm_rmid $id & shmlock $id & wait done The oops stack shows accessing NULL f_inode due to racing fput: _raw_spin_lock shmem_lock SyS_shmctl Workload 2: while true; do id=$(shmget 1 4096) shmat $id 4096 & shm_rmid $id & wait done The oops stack is similar to workload 1 due to NULL f_inode: touch_atime shmem_mmap shm_mmap mmap_region do_mmap_pgoff do_shmat SyS_shmat Workload 3: while true; do id=$(shmget 1 4096) shmlock $id shm_rmid $id & shmunlock $id & wait done The oops stack shows second fput tripping on an NULL f_inode. The first fput() completed via from shm_destroy(), but a racing thread did a get_file() and queued this fput(): locks_remove_flock __fput ____fput task_work_run do_notify_resume int_signal Fixes: c2c737a0461e ("ipc,shm: shorten critical region for shmat") Fixes: 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl") Signed-off-by: Greg Thelen Cc: Davidlohr Bueso Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ipc,shm: correct error return value in shmctl (SHM_UNLOCK)

2013-11-29T18:42:15Z

commit 3a72660b07d86d60457ca32080b1ce8c2b628ee2 upstream. Commit 2caacaa82a51 ("ipc,shm: shorten critical region for shmctl") restructured the ipc shm to shorten critical region, but introduced a path where the return value could be -EPERM, even if the operation actually was performed. Before the commit, the err return value was reset by the return value from security_shm_shmctl() after the if (!ns_capable(...)) statement. Now, we still exit the if statement with err set to -EPERM, and in the case of SHM_UNLOCK, it is not reset at all, and used as the return value from shmctl. To fix this, we only set err when errors occur, leaving the fallthrough case alone. Signed-off-by: Jesper Nilsson Cc: Davidlohr Bueso Cc: Rik van Riel Cc: Michel Lespinasse Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ipc/sem.c: update sem_otime for all operations

2013-10-18T17:55:02Z

commit 0e8c665699e953fa58dc1b0b0d09e5dce7343cc7 upstream. In commit 0a2b9d4c7967 ("ipc/sem.c: move wake_up_process out of the spinlock section"), the update of semaphore's sem_otime(last semop time) was moved to one central position (do_smart_update). But since do_smart_update() is only called for operations that modify the array, this means that wait-for-zero semops do not update sem_otime anymore. The fix is simple: Non-alter operations must update sem_otime. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Manfred Spraul Reported-by: Jia He Tested-by: Jia He Cc: Davidlohr Bueso Cc: Mike Galbraith Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ipc/sem.c: synchronize the proc interface

2013-10-18T17:55:02Z

commit d8c633766ad88527f25d9f81a5c2f083d78a2b39 upstream. The proc interface is not aware of sem_lock(), it instead calls ipc_lock_object() directly. This means that simple semop() operations can run in parallel with the proc interface. Right now, this is uncritical, because the implementation doesn't do anything that requires a proper synchronization. But it is dangerous and therefore should be fixed. Signed-off-by: Manfred Spraul Cc: Davidlohr Bueso Cc: Mike Galbraith Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

ipc/sem.c: optimize sem_lock()

2013-10-18T17:55:02Z

commit 6d07b68ce16ae9535955ba2059dedba5309c3ca1 upstream. Operations that need access to the whole array must guarantee that there are no simple operations ongoing. Right now this is achieved by spin_unlock_wait(sem->lock) on all semaphores. If complex_count is nonzero, then this spin_unlock_wait() is not necessary, because it was already performed in the past by the thread that increased complex_count and even though sem_perm.lock was dropped inbetween, no simple operation could have started, because simple operations cannot start when complex_count is non-zero. Signed-off-by: Manfred Spraul Cc: Mike Galbraith Cc: Rik van Riel Reviewed-by: Davidlohr Bueso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

ipc: drop ipc_lock_check

2013-10-18T17:55:02Z

commit 20b8875abcf2daa1dda5cf70bd6369df5e85d4c1 upstream. No remaining users, we now use ipc_obtain_object_check(). Signed-off-by: Davidlohr Bueso Cc: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

ipc, shm: drop shm_lock_check

2013-10-18T17:55:01Z

commit 7a25dd9e042b2b94202a67e5551112f4ac87285a upstream. This function was replaced by a the lockless shm_obtain_object_check(), and no longer has any users. Signed-off-by: Davidlohr Bueso Cc: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

ipc: drop ipc_lock_by_ptr

2013-10-18T17:55:01Z

commit 32a2750010981216fb788c5190fb0e646abfab30 upstream. After previous cleanups and optimizations, this function is no longer heavily used and we don't have a good reason to keep it. Update the few remaining callers and get rid of it. Signed-off-by: Davidlohr Bueso Cc: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

ipc, shm: guard against non-existant vma in shmdt(2)

2013-10-18T17:55:01Z

commit 530fcd16d87cd2417c472a581ba5a1e501556c86 upstream. When !CONFIG_MMU there's a chance we can derefence a NULL pointer when the VM area isn't found - check the return value of find_vma(). Also, remove the redundant -EINVAL return: retval is set to the proper return code and *only* changed to 0, when we actually unmap the segments. Signed-off-by: Davidlohr Bueso Cc: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman

ipc: document general ipc locking scheme

2013-10-18T17:55:01Z

commit 05603c44a7627793219b0bd9a7b236099dc9cd9d upstream. As suggested by Andrew, add a generic initial locking scheme used throughout all sysv ipc mechanisms. Documenting the ids rwsem, how rcu can be enough to do the initial checks and when to actually acquire the kern_ipc_perm.lock spinlock. I found that adding it to util.c was generic enough. Signed-off-by: Davidlohr Bueso Tested-by: Sedat Dilek Cc: Rik van Riel Cc: Manfred Spraul Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Cc: Mike Galbraith Signed-off-by: Greg Kroah-Hartman