Bug 2495958 (CVE-2026-53337)

Summary: CVE-2026-53337 kernel: net: bonding: fix NULL pointer dereference in bond_do_ioctl()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's bonding interface. A local user with CAP_NET_ADMIN capability can trigger a NULL pointer dereference by calling a bonding ioctl (input/output control) with a non-existent slave interface name. This vulnerability can lead to a kernel oops, resulting in a local Denial of Service (DoS) for the affected system.
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Description OSIDB Bzimport 2026-07-01 14:03:42 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: bonding: fix NULL pointer dereference in bond_do_ioctl()

In bond_do_ioctl(), slave_dev is obtained via __dev_get_by_name() which
can return NULL if the requested interface name does not exist. However,
the subsequent slave_dbg() call is placed before the NULL check:

    slave_dev = __dev_get_by_name(net, ifr->ifr_slave);
    slave_dbg(bond_dev, slave_dev, "slave_dev=%p:\n", slave_dev); //here
    if (!slave_dev)
        return -ENODEV;

The slave_dbg() macro expands to netdev_dbg(bond_dev, "(slave %s): " fmt,
(slave_dev)->name, ...) which unconditionally dereferences slave_dev->name
before the NULL check is performed. This results in a NULL pointer
dereference kernel oops when a user calls bonding ioctl (e.g.
SIOCBONDENSLAVE, SIOCBONDRELEASE, etc.) with a non-existent slave
interface name.

This is reachable from userspace via the bonding ioctl interface with
CAP_NET_ADMIN capability, making it a potential local denial-of-service
vector.

Fix by moving the slave_dbg() call after the NULL check.

Comment 1 Mauro Matteo Cascella 2026-07-01 15:44:05 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026070143-CVE-2026-53337-f2ec@gregkh/T