diff options
| author | Jann Horn <jannh@google.com> | 2018-07-06 22:48:03 +0200 |
|---|---|---|
| committer | Jason Gunthorpe <jgg@mellanox.com> | 2018-07-09 13:15:12 -0600 |
| commit | 60e6627f12a78203a093ca05b7bca15627747d81 (patch) | |
| tree | 76dcde09c85d2f3e1ec739140172713546b2d115 /drivers/infiniband/hw/mlx5/cong.c | |
| parent | 222c7b1fd4dcc596e4a21dc93f49d9c976f7e314 (diff) | |
IB/mlx5: fix uaccess beyond "count" in debugfs read/write handlers
In general, accessing userspace memory beyond the length of the supplied
buffer in VFS read/write handlers can lead to both kernel memory corruption
(via kernel_read()/kernel_write(), which can e.g. be triggered via
sys_splice()) and privilege escalation inside userspace.
In this case, the affected files are in debugfs (and should therefore only
be accessible to root), and the read handlers check that *pos is zero
(meaning that at least sys_splice() can't trigger kernel memory
corruption). Because of the root requirement, this is not a security fix,
but rather a cleanup.
For the read handlers, fix it by using simple_read_from_buffer() instead
of custom logic. Add min() calls to the write handlers.
Fixes: 4a2da0b8c078 ("IB/mlx5: Add debug control parameters for congestion control")
Fixes: e126ba97dba9 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Diffstat (limited to 'drivers/infiniband/hw/mlx5/cong.c')
| -rw-r--r-- | drivers/infiniband/hw/mlx5/cong.c | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/drivers/infiniband/hw/mlx5/cong.c b/drivers/infiniband/hw/mlx5/cong.c index 985fa2637390..7e4e358a4fd8 100644 --- a/drivers/infiniband/hw/mlx5/cong.c +++ b/drivers/infiniband/hw/mlx5/cong.c @@ -359,9 +359,6 @@ static ssize_t get_param(struct file *filp, char __user *buf, size_t count, int ret; char lbuf[11]; - if (*pos) - return 0; - ret = mlx5_ib_get_cc_params(param->dev, param->port_num, offset, &var); if (ret) return ret; @@ -370,11 +367,7 @@ static ssize_t get_param(struct file *filp, char __user *buf, size_t count, if (ret < 0) return ret; - if (copy_to_user(buf, lbuf, ret)) - return -EFAULT; - - *pos += ret; - return ret; + return simple_read_from_buffer(buf, count, pos, lbuf, ret); } static const struct file_operations dbg_cc_fops = { |