Vulnerability Details CVE-2021-47125
In the Linux kernel, the following vulnerability has been resolved:
sch_htb: fix refcount leak in htb_parent_to_leaf_offload
The commit ae81feb7338c ("sch_htb: fix null pointer dereference
on a null new_q") fixes a NULL pointer dereference bug, but it
is not correct.
Because htb_graft_helper properly handles the case when new_q
is NULL, and after the previous patch by skipping this call
which creates an inconsistency : dev_queue->qdisc will still
point to the old qdisc, but cl->parent->leaf.q will point to
the new one (which will be noop_qdisc, because new_q was NULL).
The code is based on an assumption that these two pointers are
the same, so it can lead to refcount leaks.
The correct fix is to add a NULL pointer check to protect
qdisc_refcount_inc inside htb_parent_to_leaf_offload.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 2.6%
CVSS Severity
CVSS v3 Score 5.5
References
Products affected by CVE-2021-47125
-
cpe:2.3:o:linux:linux_kernel:5.12
-
cpe:2.3:o:linux:linux_kernel:5.12.1
-
cpe:2.3:o:linux:linux_kernel:5.12.2
-
cpe:2.3:o:linux:linux_kernel:5.12.3
-
cpe:2.3:o:linux:linux_kernel:5.12.4
-
cpe:2.3:o:linux:linux_kernel:5.12.5
-
cpe:2.3:o:linux:linux_kernel:5.12.6
-
cpe:2.3:o:linux:linux_kernel:5.12.7
-
cpe:2.3:o:linux:linux_kernel:5.12.8
-
cpe:2.3:o:linux:linux_kernel:5.12.9
-
cpe:2.3:o:linux:linux_kernel:5.13