| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 45/68] platform/chrome: cros_ec_dev - double fetch bug in ioctl | Date | Mon, 8 Aug 2016 21:11:20 +0200 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Dan Carpenter <dan.carpenter@oracle.com>
commit 096cdc6f52225835ff503f987a0d68ef770bb78e upstream.
We verify "u_cmd.outsize" and "u_cmd.insize" but we need to make sure that those values have not changed between the two copy_from_user() calls. Otherwise it could lead to a buffer overflow.
Additionally, cros_ec_cmd_xfer() can set s_cmd->insize to a lower value. We should use the new smaller value so we don't copy too much data to the user.
Reported-by: Pengfei Wang <wpengfeinudt@gmail.com> Fixes: a841178445bb ('mfd: cros_ec: Use a zero-length array for command data') Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Gwendal Grignou <gwendal@chromium.org> Signed-off-by: Olof Johansson <olof@lixom.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/platform/chrome/cros_ec_dev.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/platform/chrome/cros_ec_dev.c +++ b/drivers/platform/chrome/cros_ec_dev.c @@ -147,13 +147,19 @@ static long ec_device_ioctl_xcmd(struct goto exit; } + if (u_cmd.outsize != s_cmd->outsize || + u_cmd.insize != s_cmd->insize) { + ret = -EINVAL; + goto exit; + } + s_cmd->command += ec->cmd_offset; ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd); /* Only copy data to userland if data was received. */ if (ret < 0) goto exit; - if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + u_cmd.insize)) + if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize)) ret = -EFAULT; exit: kfree(s_cmd);
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