shmdt: use i_size_read() instead of ->i_size (07a46ed2) · Commits · 戴 / test

Andrew Morton noted http://lkml.kernel.org/r/20141104142027.a7a0d010772d84560b445f59@linux-foundation.org that the shmdt uses inode->i_size outside of i_mutex being held. There is one more case in shm.c in shm_destroy(). This converts both users over to use i_size_read(). Signed-off-by:

Dave Hansen <dave.hansen@linux.intel.com> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Signed-off-by:

ipc/shm.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -219,7 +219,8 @@ static void shm_destroy(struct ipc_namespace ns, struct shmid_kernel shp)
		if (!is_file_hugepages(shm_file))
		shmem_lock(shm_file, 0, shp->mlock_user);
		else if (shp->mlock_user)
		user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user);
		user_shm_unlock(i_size_read(file_inode(shm_file)),
		shp->mlock_user);
		fput(shm_file);
		ipc_rcu_putref(shp, shm_rcu_free);
		}
		@@ -1280,7 +1281,7 @@ SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
		* in the range we are unmapping.
		*/
		file = vma->vm_file;
		size = file_inode(file)->i_size;
		size = i_size_read(file_inode(vma->vm_file));
		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
		/*
		* We discovered the size of the shm segment, so