liveupdate: luo_core: fix redundant bound check in luo_ioctl()

The kernel test robot reported a Smatch warning:
kernel/liveupdate/luo_core.c:402 luo_ioctl() warn: unsigned 'nr' is
never less than zero.

This occurs because 'nr' is unsigned and LIVEUPDATE_CMD_BASE is currently
defined as 0, making the check (nr < LIVEUPDATE_CMD_BASE) always false.

Remove the explicit lower bound check.  The logic remains correct because
'nr' is unsigned; if nr is less than LIVEUPDATE_CMD_BASE, the expression
(nr - LIVEUPDATE_CMD_BASE) will wrap around to a large positive value.
This will inevitably be larger than ARRAY_SIZE(luo_ioctl_ops) and be
caught by the upper bound check.

Link: https://lkml.kernel.org/r/20251130010919.1488230-1-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511280300.6pvBmXUS-lkp@intel.com/
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: David Matlack <dmatlack@google.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c
index f7ecaf7740d19dc33114536bc4adb4949f1be2d7..944663d99dd9f3a6933cb3367cad7c9fc8dc55d0 100644 (file)
--- a/kernel/liveupdate/luo_core.c
+++ b/kernel/liveupdate/luo_core.c
@@ -399,10 +399,8 @@ static long luo_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
        int err;
 
        nr = _IOC_NR(cmd);
-       if (nr < LIVEUPDATE_CMD_BASE ||
-           (nr - LIVEUPDATE_CMD_BASE) >= ARRAY_SIZE(luo_ioctl_ops)) {
+       if (nr - LIVEUPDATE_CMD_BASE >= ARRAY_SIZE(luo_ioctl_ops))
                return -EINVAL;
-       }
 
        ucmd.ubuffer = (void __user *)arg;
        err = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer);