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i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr()
i2cdev_ioctl_rdwr() allocates i2c_msg.buf using memdup_user(), which returns ZERO_SIZE_PTR if i2c_msg.len is zero. Currently i2cdev_ioctl_rdwr() always dereferences the buf pointer in case of I2C_M_RD | I2C_M_RECV_LEN transfer. That causes a kernel oops in case of zero len. Let's check the len against zero before dereferencing buf pointer. This issue was triggered by syzkaller. Signed-off-by: Alexander Popov <alex.popov@linux.com> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> [wsa: use '< 1' instead of '!' for easier readability] Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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1 changed files with 1 additions and 1 deletions
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@ -280,7 +280,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
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*/
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if (msgs[i].flags & I2C_M_RECV_LEN) {
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if (!(msgs[i].flags & I2C_M_RD) ||
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msgs[i].buf[0] < 1 ||
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msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
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msgs[i].len < msgs[i].buf[0] +
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I2C_SMBUS_BLOCK_MAX) {
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res = -EINVAL;
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