linux-kernel - [PATCH] liveupdate: luo_core: fix redundant bound check in luo

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251130010919.1488230-1-pasha.tatashin@soleen.com>
Date: Sat, 29 Nov 2025 20:09:19 -0500
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: pratyush@...nel.org,
	pasha.tatashin@...een.com,
	rppt@...nel.org,
	dmatlack@...gle.com,
	akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH] 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.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511280300.6pvBmXUS-lkp@intel.com/
Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
---
 kernel/liveupdate/luo_core.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/liveupdate/luo_core.c b/kernel/liveupdate/luo_core.c
index 69298d82f404..7a9ef16b37d8 100644
--- a/kernel/liveupdate/luo_core.c
+++ b/kernel/liveupdate/luo_core.c
@@ -404,10 +404,8 @@ 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);

base-commit: 7d31f578f3230f3b7b33b0930b08f9afd8429817
-- 
2.52.0.487.g5c8c507ade-goog