kill_ioctx() sets ctx->dead and removes ctx from ->ioctx_table "atomically" under mm->ioctx_lock, so aio_ring_remap() can never see a dead ctx.
And even -EINVAL doesn't look necessary. Yes, if mremap() races with kill_ioctx() vm_munmap(ctx->mmap_base, ctx->mmap_size) can unmap the wrong region. In this case the buggy application should blame itself. And there are other reasons why that vm_munmap() can be wrong. Say, an application can mremap() the part of aio region and then do io_destroy(). We could change aio_ring_remap() to verify vma->that vma_end - vma->vma_start == ctx->mmap_size but this won't help if the application does munmap() instead. Signed-off-by: Oleg Nesterov <[email protected]> --- fs/aio.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 480440f..893d300 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -325,14 +325,11 @@ static int aio_ring_remap(struct file *file, struct vm_area_struct *vma) rcu_read_lock(); table = rcu_dereference(mm->ioctx_table); for (i = 0; i < table->nr; i++) { - struct kioctx *ctx; + struct kioctx *ctx = table->table[i]; - ctx = table->table[i]; if (ctx && ctx->aio_ring_file == file) { - if (!atomic_read(&ctx->dead)) { - ctx->user_id = ctx->mmap_base = vma->vm_start; - res = 0; - } + ctx->user_id = ctx->mmap_base = vma->vm_start; + res = 0; break; } } -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
