CVE - CVE-2025-37953

CVE-ID
CVE-2025-37953	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): \|-> fq_codel_dequeue() \|-> qdisc_tree_reduce_backlog() \|-> htb_qlen_notify() \|-> htb_deactivate() \|-> htb_next_rb_node() \|-> htb_deactivate() For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulnerable here. For htb_deactivate(), although we checked qlen before calling it, in case of qlen==0 after qdisc_tree_reduce_backlog(), we may call it again which triggers the warning inside. To fix the issues here, we need to: 1) Make htb_deactivate() idempotent, that is, simply return if we already call it before. 2) Make htb_next_rb_node() safe against ptr==NULL. Many thanks to Alan for testing and for the reproducer.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07 URL:https://git.kernel.org/stable/c/31ff70ad39485698cf779f2078132d80b57f6c07 MISC:https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71 URL:https://git.kernel.org/stable/c/3769478610135e82b262640252d90f6efb05be71 MISC:https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d URL:https://git.kernel.org/stable/c/98cd7ed92753090a714f0802d4434314526fe61d MISC:https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b URL:https://git.kernel.org/stable/c/c4792b9e38d2f61b07eac72f10909fa76130314b MISC:https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0 URL:https://git.kernel.org/stable/c/c928dd4f6bf0c25c72b11824a1e9ac9bd37296a0
Assigning CNA
kernel.org
Date Record Created
20250416	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20250416)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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