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| author | Dan Carpenter <dan.carpenter@oracle.com> | 2016-06-21 16:58:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-10 12:54:47 +0200 |
| commit | 68b0cefc0358c3e3364fd520bf11c9c7b43be45b (patch) | |
| tree | bbc7b7686e333459cdc0ce5a7cb20bf28b10a59b | |
| parent | f54a878c9946fd22a9d7b0088f3f15b5eee1e8b7 (diff) | |
| download | lwn-68b0cefc0358c3e3364fd520bf11c9c7b43be45b.tar.gz lwn-68b0cefc0358c3e3364fd520bf11c9c7b43be45b.zip | |
platform/chrome: cros_ec_dev - double fetch bug in ioctl
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>
| -rw-r--r-- | drivers/platform/chrome/cros_ec_dev.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/platform/chrome/cros_ec_dev.c b/drivers/platform/chrome/cros_ec_dev.c index d45cd254ed1c..2b331d5b9e79 100644 --- 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 cros_ec_dev *ec, void __user *arg) 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); |