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| author | Mingyu Wang <25181214217@stu.xidian.edu.cn> | 2026-04-27 05:57:45 +0300 |
|---|---|---|
| committer | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2026-05-04 12:31:35 +0300 |
| commit | 617eb7c0961a8dfcfc811844a6396e406b2923ea (patch) | |
| tree | 53b66db6c5eda2fefd6e61ba200b6ddf76dd4fb9 | |
| parent | 9998e388be9930c106eb5904c23ecf2162407527 (diff) | |
| download | linux-617eb7c0961a8dfcfc811844a6396e406b2923ea.tar.xz | |
i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl
While fuzzing with Syzkaller, a persistent `schedule_timeout: wrong
timeout value` warning was observed, accompanied by SMBus controller
state machine corruption.
The I2C_TIMEOUT ioctl accepts a user-provided timeout in multiples of
10 ms. The user argument is checked against INT_MAX, but it is
subsequently multiplied by 10 before being passed to msecs_to_jiffies().
A malicious user can pass a large value (e.g., 429496729) that passes
the `arg > INT_MAX` check but overflows when multiplied by 10. This
results in a truncated 32-bit unsigned value that bypasses the
internal `(int)m < 0` check in `msecs_to_jiffies()`.
The truncated value is then assigned to `client->adapter->timeout`
(a signed 32-bit int), which is reinterpreted as a negative number.
When passed to wait_for_completion_timeout(), this negative value
undergoes sign extension to a 64-bit unsigned long, triggering the
`schedule_timeout` warning and causing premature returns. This leaves
the SMBus state machine in an unrecoverable state, constituting a
local Denial of Service (DoS).
Fix this by bounding the user argument to `INT_MAX / 10`.
Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn>
[wsa: move the comment as well]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
| -rw-r--r-- | drivers/i2c/i2c-dev.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c index 7bbe0263411e..ccaac5e29f90 100644 --- a/drivers/i2c/i2c-dev.c +++ b/drivers/i2c/i2c-dev.c @@ -487,12 +487,13 @@ static long i2cdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) client->adapter->retries = arg; break; case I2C_TIMEOUT: - if (arg > INT_MAX) + /* + * For historical reasons, user-space sets the timeout value in + * units of 10 ms. + */ + if (arg > INT_MAX / 10) return -EINVAL; - /* For historical reasons, user-space sets the timeout - * value in units of 10 ms. - */ client->adapter->timeout = msecs_to_jiffies(arg * 10); break; default: |