6.12-stable review patch. If anyone has any objections, please let me know.
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From: Jacob Keller jacob.e.keller@intel.com
[ Upstream commit 9fcdb1c3c4ba134434694c001dbff343f1ffa319 ]
The 'command' and 'netdev_ops' debugfs files are a legacy debugging interface supported by the i40e driver since its early days by commit 02e9c290814c ("i40e: debugfs interface").
Both of these debugfs files provide a read handler which is mostly useless, and which is implemented with questionable logic. They both use a static 256 byte buffer which is initialized to the empty string. In the case of the 'command' file this buffer is literally never used and simply wastes space. In the case of the 'netdev_ops' file, the last command written is saved here.
On read, the files contents are presented as the name of the device followed by a colon and then the contents of their respective static buffer. For 'command' this will always be "<device>: ". For 'netdev_ops', this will be "<device>: <last command written>". But note the buffer is shared between all devices operated by this module. At best, it is mostly meaningless information, and at worse it could be accessed simultaneously as there doesn't appear to be any locking mechanism.
We have also recently received multiple reports for both read functions about their use of snprintf and potential overflow that could result in reading arbitrary kernel memory. For the 'command' file, this is definitely impossible, since the static buffer is always zero and never written to. For the 'netdev_ops' file, it does appear to be possible, if the user carefully crafts the command input, it will be copied into the buffer, which could be large enough to cause snprintf to truncate, which then causes the copy_to_user to read beyond the length of the buffer allocated by kzalloc.
A minimal fix would be to replace snprintf() with scnprintf() which would cap the return to the number of bytes written, preventing an overflow. A more involved fix would be to drop the mostly useless static buffers, saving 512 bytes and modifying the read functions to stop needing those as input.
Instead, lets just completely drop the read access to these files. These are debug interfaces exposed as part of debugfs, and I don't believe that dropping read access will break any script, as the provided output is pretty useless. You can find the netdev name through other more standard interfaces, and the 'netdev_ops' interface can easily result in garbage if you issue simultaneous writes to multiple devices at once.
In order to properly remove the i40e_dbg_netdev_ops_buf, we need to refactor its write function to avoid using the static buffer. Instead, use the same logic as the i40e_dbg_command_write, with an allocated buffer. Update the code to use this instead of the static buffer, and ensure we free the buffer on exit. This fixes simultaneous writes to 'netdev_ops' on multiple devices, and allows us to remove the now unused static buffer along with removing the read access.
Fixes: 02e9c290814c ("i40e: debugfs interface") Reported-by: Kunwu Chan chentao@kylinos.cn Closes: https://lore.kernel.org/intel-wired-lan/20231208031950.47410-1-chentao@kylin... Reported-by: Wang Haoran haoranwangsec@gmail.com Closes: https://lore.kernel.org/all/CANZ3JQRRiOdtfQJoP9QM=6LS1Jto8PGBGw6y7-TL=BcnzHQ... Reported-by: Amir Mohammad Jahangirzad a.jahangirzad@gmail.com Closes: https://lore.kernel.org/all/20250722115017.206969-1-a.jahangirzad@gmail.com/ Signed-off-by: Jacob Keller jacob.e.keller@intel.com Reviewed-by: Dawid Osuchowski dawid.osuchowski@linux.intel.com Reviewed-by: Aleksandr Loktionov aleksandr.loktionov@intel.com Reviewed-by: Simon Horman horms@kernel.org Reviewed-by: Kunwu Chan kunwu.chan@linux.dev Tested-by: Rinitha S sx.rinitha@intel.com (A Contingent worker at Intel) Signed-off-by: Tony Nguyen anthony.l.nguyen@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../net/ethernet/intel/i40e/i40e_debugfs.c | 123 +++--------------- 1 file changed, 19 insertions(+), 104 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c index 208c2f0857b61..ded8f43fdf068 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_debugfs.c +++ b/drivers/net/ethernet/intel/i40e/i40e_debugfs.c @@ -40,48 +40,6 @@ static struct i40e_vsi *i40e_dbg_find_vsi(struct i40e_pf *pf, int seid) * setup, adding or removing filters, or other things. Many of * these will be useful for some forms of unit testing. **************************************************************/ -static char i40e_dbg_command_buf[256] = ""; - -/** - * i40e_dbg_command_read - read for command datum - * @filp: the opened file - * @buffer: where to write the data for the user to read - * @count: the size of the user's buffer - * @ppos: file position offset - **/ -static ssize_t i40e_dbg_command_read(struct file *filp, char __user *buffer, - size_t count, loff_t *ppos) -{ - struct i40e_pf *pf = filp->private_data; - struct i40e_vsi *main_vsi; - int bytes_not_copied; - int buf_size = 256; - char *buf; - int len; - - /* don't allow partial reads */ - if (*ppos != 0) - return 0; - if (count < buf_size) - return -ENOSPC; - - buf = kzalloc(buf_size, GFP_KERNEL); - if (!buf) - return -ENOSPC; - - main_vsi = i40e_pf_get_main_vsi(pf); - len = snprintf(buf, buf_size, "%s: %s\n", main_vsi->netdev->name, - i40e_dbg_command_buf); - - bytes_not_copied = copy_to_user(buffer, buf, len); - kfree(buf); - - if (bytes_not_copied) - return -EFAULT; - - *ppos = len; - return len; -}
static char *i40e_filter_state_string[] = { "INVALID", @@ -1621,7 +1579,6 @@ static ssize_t i40e_dbg_command_write(struct file *filp, static const struct file_operations i40e_dbg_command_fops = { .owner = THIS_MODULE, .open = simple_open, - .read = i40e_dbg_command_read, .write = i40e_dbg_command_write, };
@@ -1630,48 +1587,6 @@ static const struct file_operations i40e_dbg_command_fops = { * The netdev_ops entry in debugfs is for giving the driver commands * to be executed from the netdev operations. **************************************************************/ -static char i40e_dbg_netdev_ops_buf[256] = ""; - -/** - * i40e_dbg_netdev_ops_read - read for netdev_ops datum - * @filp: the opened file - * @buffer: where to write the data for the user to read - * @count: the size of the user's buffer - * @ppos: file position offset - **/ -static ssize_t i40e_dbg_netdev_ops_read(struct file *filp, char __user *buffer, - size_t count, loff_t *ppos) -{ - struct i40e_pf *pf = filp->private_data; - struct i40e_vsi *main_vsi; - int bytes_not_copied; - int buf_size = 256; - char *buf; - int len; - - /* don't allow partal reads */ - if (*ppos != 0) - return 0; - if (count < buf_size) - return -ENOSPC; - - buf = kzalloc(buf_size, GFP_KERNEL); - if (!buf) - return -ENOSPC; - - main_vsi = i40e_pf_get_main_vsi(pf); - len = snprintf(buf, buf_size, "%s: %s\n", main_vsi->netdev->name, - i40e_dbg_netdev_ops_buf); - - bytes_not_copied = copy_to_user(buffer, buf, len); - kfree(buf); - - if (bytes_not_copied) - return -EFAULT; - - *ppos = len; - return len; -}
/** * i40e_dbg_netdev_ops_write - write into netdev_ops datum @@ -1685,35 +1600,36 @@ static ssize_t i40e_dbg_netdev_ops_write(struct file *filp, size_t count, loff_t *ppos) { struct i40e_pf *pf = filp->private_data; + char *cmd_buf, *buf_tmp; int bytes_not_copied; struct i40e_vsi *vsi; - char *buf_tmp; int vsi_seid; int i, cnt;
/* don't allow partial writes */ if (*ppos != 0) return 0; - if (count >= sizeof(i40e_dbg_netdev_ops_buf)) - return -ENOSPC;
- memset(i40e_dbg_netdev_ops_buf, 0, sizeof(i40e_dbg_netdev_ops_buf)); - bytes_not_copied = copy_from_user(i40e_dbg_netdev_ops_buf, - buffer, count); - if (bytes_not_copied) + cmd_buf = kzalloc(count + 1, GFP_KERNEL); + if (!cmd_buf) + return count; + bytes_not_copied = copy_from_user(cmd_buf, buffer, count); + if (bytes_not_copied) { + kfree(cmd_buf); return -EFAULT; - i40e_dbg_netdev_ops_buf[count] = '\0'; + } + cmd_buf[count] = '\0';
- buf_tmp = strchr(i40e_dbg_netdev_ops_buf, '\n'); + buf_tmp = strchr(cmd_buf, '\n'); if (buf_tmp) { *buf_tmp = '\0'; - count = buf_tmp - i40e_dbg_netdev_ops_buf + 1; + count = buf_tmp - cmd_buf + 1; }
- if (strncmp(i40e_dbg_netdev_ops_buf, "change_mtu", 10) == 0) { + if (strncmp(cmd_buf, "change_mtu", 10) == 0) { int mtu;
- cnt = sscanf(&i40e_dbg_netdev_ops_buf[11], "%i %i", + cnt = sscanf(&cmd_buf[11], "%i %i", &vsi_seid, &mtu); if (cnt != 2) { dev_info(&pf->pdev->dev, "change_mtu <vsi_seid> <mtu>\n"); @@ -1735,8 +1651,8 @@ static ssize_t i40e_dbg_netdev_ops_write(struct file *filp, dev_info(&pf->pdev->dev, "Could not acquire RTNL - please try again\n"); }
- } else if (strncmp(i40e_dbg_netdev_ops_buf, "set_rx_mode", 11) == 0) { - cnt = sscanf(&i40e_dbg_netdev_ops_buf[11], "%i", &vsi_seid); + } else if (strncmp(cmd_buf, "set_rx_mode", 11) == 0) { + cnt = sscanf(&cmd_buf[11], "%i", &vsi_seid); if (cnt != 1) { dev_info(&pf->pdev->dev, "set_rx_mode <vsi_seid>\n"); goto netdev_ops_write_done; @@ -1756,8 +1672,8 @@ static ssize_t i40e_dbg_netdev_ops_write(struct file *filp, dev_info(&pf->pdev->dev, "Could not acquire RTNL - please try again\n"); }
- } else if (strncmp(i40e_dbg_netdev_ops_buf, "napi", 4) == 0) { - cnt = sscanf(&i40e_dbg_netdev_ops_buf[4], "%i", &vsi_seid); + } else if (strncmp(cmd_buf, "napi", 4) == 0) { + cnt = sscanf(&cmd_buf[4], "%i", &vsi_seid); if (cnt != 1) { dev_info(&pf->pdev->dev, "napi <vsi_seid>\n"); goto netdev_ops_write_done; @@ -1775,21 +1691,20 @@ static ssize_t i40e_dbg_netdev_ops_write(struct file *filp, dev_info(&pf->pdev->dev, "napi called\n"); } } else { - dev_info(&pf->pdev->dev, "unknown command '%s'\n", - i40e_dbg_netdev_ops_buf); + dev_info(&pf->pdev->dev, "unknown command '%s'\n", cmd_buf); dev_info(&pf->pdev->dev, "available commands\n"); dev_info(&pf->pdev->dev, " change_mtu <vsi_seid> <mtu>\n"); dev_info(&pf->pdev->dev, " set_rx_mode <vsi_seid>\n"); dev_info(&pf->pdev->dev, " napi <vsi_seid>\n"); } netdev_ops_write_done: + kfree(cmd_buf); return count; }
static const struct file_operations i40e_dbg_netdev_ops_fops = { .owner = THIS_MODULE, .open = simple_open, - .read = i40e_dbg_netdev_ops_read, .write = i40e_dbg_netdev_ops_write, };