iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

IB/mlx5: fix uaccess beyond "count" in debugfs read/write handlers

Browse Source 
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: 4a2da0b8c0 ("IB/mlx5: Add debug control parameters for congestion control")
Fixes: e126ba97db ("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>
This commit is contained in:
Jann Horn 2018-07-06 22:48:03 +02:00 committed by Jason Gunthorpe
parent 222c7b1fd4
commit 60e6627f12
2 changed files with 9 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/infiniband/hw/mlx5/cong.c
View File

@ -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 = {

32
drivers/infiniband/hw/mlx5/mr.c
View File

@ -271,16 +271,16 @@ static ssize_t size_write(struct file *filp, const char __user *buf,
{
struct mlx5_cache_ent *ent = filp->private_data;
struct mlx5_ib_dev *dev = ent->dev;
char lbuf[20];
char lbuf[20] = {0};
u32 var;
int err;
int c;
if (copy_from_user(lbuf, buf, sizeof(lbuf)))
count = min(count, sizeof(lbuf) - 1);
if (copy_from_user(lbuf, buf, count))
return -EFAULT;
c = order2idx(dev, ent->order);
lbuf[sizeof(lbuf) - 1] = 0;
if (sscanf(lbuf, "%u", &var) != 1)
return -EINVAL;
@ -310,19 +310,11 @@ static ssize_t size_read(struct file *filp, char __user *buf, size_t count,
char lbuf[20];
int err;
if (*pos)
return 0;
err = snprintf(lbuf, sizeof(lbuf), "%d\n", ent->size);
if (err < 0)
return err;
if (copy_to_user(buf, lbuf, err))
return -EFAULT;
*pos += err;
return err;
return simple_read_from_buffer(buf, count, pos, lbuf, err);
}
static const struct file_operations size_fops = {
@ -337,16 +329,16 @@ static ssize_t limit_write(struct file *filp, const char __user *buf,
{
struct mlx5_cache_ent *ent = filp->private_data;
struct mlx5_ib_dev *dev = ent->dev;
char lbuf[20];
char lbuf[20] = {0};
u32 var;
int err;
int c;
if (copy_from_user(lbuf, buf, sizeof(lbuf)))
count = min(count, sizeof(lbuf) - 1);
if (copy_from_user(lbuf, buf, count))
return -EFAULT;
c = order2idx(dev, ent->order);
lbuf[sizeof(lbuf) - 1] = 0;
if (sscanf(lbuf, "%u", &var) != 1)
return -EINVAL;
@ -372,19 +364,11 @@ static ssize_t limit_read(struct file *filp, char __user *buf, size_t count,
char lbuf[20];
int err;
if (*pos)
return 0;
err = snprintf(lbuf, sizeof(lbuf), "%d\n", ent->limit);
if (err < 0)
return err;
if (copy_to_user(buf, lbuf, err))
return -EFAULT;
*pos += err;
return err;
return simple_read_from_buffer(buf, count, pos, lbuf, err);
}
static const struct file_operations limit_fops = {