If we don't limit cmd.ne then the multiplications can overflow. This will allocate a small amount of RAM successfully for the "resp" and "wc" buffers. The heap will get corrupted when we call ib_poll_cq().
Documentation/infiniband/user_verbs.txt suggests this function is meant for unprivileged access. I chose to limit the number of entries to 1000. That limits the allocations to 52kb of RAM at the most. I didn't want to choose a lower number and break userspace for someone. Also we don't necessarily fill the "resp" buffer so I changed the kmalloc() to a kzalloc() to avoid an information leak. CC: [email protected] Signed-off-by: Dan Carpenter <[email protected]> diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h --- a/drivers/infiniband/core/uverbs.h +++ b/drivers/infiniband/core/uverbs.h @@ -162,6 +162,7 @@ void ib_uverbs_srq_event_handler(struct ib_event *event, void *context_ptr); void ib_uverbs_event_handler(struct ib_event_handler *handler, struct ib_event *event); +#define UVERBS_MAX_NUM_ENTRIES 1000 #define IB_UVERBS_DECLARE_CMD(name) \ ssize_t ib_uverbs_##name(struct ib_uverbs_file *file, \ const char __user *buf, int in_len, \ diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c --- a/drivers/infiniband/core/uverbs_cmd.c +++ b/drivers/infiniband/core/uverbs_cmd.c @@ -906,12 +906,15 @@ ssize_t ib_uverbs_poll_cq(struct ib_uverbs_file *file, if (copy_from_user(&cmd, buf, sizeof cmd)) return -EFAULT; + if (cmd.ne > UVERBS_MAX_NUM_ENTRIES) + return -EINVAL; + wc = kmalloc(cmd.ne * sizeof *wc, GFP_KERNEL); if (!wc) return -ENOMEM; rsize = sizeof *resp + cmd.ne * sizeof(struct ib_uverbs_wc); - resp = kmalloc(rsize, GFP_KERNEL); + resp = kzalloc(rsize, GFP_KERNEL); if (!resp) { ret = -ENOMEM; goto out_wc; -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
