sctp: use call_rcu to free endpoint

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Summary

CVECVE-2021-46929
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-02-27 10:15:07 UTC
Updated2026-08-04 10:16:37 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: sctp: use call_rcu to free endpoint This patch is to delay the endpoint free by calling call_rcu() to fix another use-after-free issue in sctp_sock_dump(): BUG: KASAN: use-after-free in __lock_acquire+0x36d9/0x4c20 Call Trace: __lock_acquire+0x36d9/0x4c20 kernel/locking/lockdep.c:3218 lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3844 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:168 spin_lock_bh include/linux/spinlock.h:334 [inline] __lock_sock+0x203/0x350 net/core/sock.c:2253 lock_sock_nested+0xfe/0x120 net/core/sock.c:2774 lock_sock include/net/sock.h:1492 [inline] sctp_sock_dump+0x122/0xb20 net/sctp/diag.c:324 sctp_for_each_transport+0x2b5/0x370 net/sctp/socket.c:5091 sctp_diag_dump+0x3ac/0x660 net/sctp/diag.c:527 __inet_diag_dump+0xa8/0x140 net/ipv4/inet_diag.c:1049 inet_diag_dump+0x9b/0x110 net/ipv4/inet_diag.c:1065 netlink_dump+0x606/0x1080 net/netlink/af_netlink.c:2244 __netlink_dump_start+0x59a/0x7c0 net/netlink/af_netlink.c:2352 netlink_dump_start include/linux/netlink.h:216 [inline] inet_diag_handler_cmd+0x2ce/0x3f0 net/ipv4/inet_diag.c:1170 __sock_diag_cmd net/core/sock_diag.c:232 [inline] sock_diag_rcv_msg+0x31d/0x410 net/core/sock_diag.c:263 netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477 sock_diag_rcv+0x2a/0x40 net/core/sock_diag.c:274 This issue occurs when asoc is peeled off and the old sk is freed after getting it by asoc->base.sk and before calling lock_sock(sk). To prevent the sk free, as a holder of the sk, ep should be alive when calling lock_sock(). This patch uses call_rcu() and moves sock_put and ep free into sctp_endpoint_destroy_rcu(), so that it's safe to try to hold the ep under rcu_read_lock in sctp_transport_traverse_process(). If sctp_endpoint_hold() returns true, it means this ep is still alive and we have held it and can continue to dump it; If it returns false, it means this ep is dead and can be freed after rcu_read_unlock, and we should skip it. In sctp_sock_dump(), after locking the sk, if this ep is different from tsp->asoc->ep, it means during this dumping, this asoc was peeled off before calling lock_sock(), and the sk should be skipped; If this ep is the same with tsp->asoc->ep, it means no peeloff happens on this asoc, and due to lock_sock, no peeloff will happen either until release_sock. Note that delaying endpoint free won't delay the port release, as the port release happens in sctp_endpoint_destroy() before calling call_rcu(). Also, freeing endpoint by call_rcu() makes it safe to access the sk by asoc->base.sk in sctp_assocs_seq_show() and sctp_rcv(). Thanks Jones to bring this issue up. v1->v2: - improve the changelog. - add kfree(ep) into sctp_endpoint_destroy_rcu(), as Jakub noticed.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-416

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary5.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab 8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e git Not specified
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec git Not specified
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab 831de271452b87657fcf8d715ee20519b79caef5 git Not specified
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab 769d14abd35e0e153b5149c3e1e989a9d719e3ff git Not specified
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab 75799e71df1da11394740b43ae5686646179561d git Not specified
CNA Linux Linux affected d25adbeb0cdb860fb39e09cdd025e9cfc954c5ab 5ec7d18d1813a5bead0b495045606c93873aecbb git Not specified
CNA Linux Linux affected 4.14 Not specified
CNA Linux Linux unaffected 4.14 semver Not specified
CNA Linux Linux unaffected 4.14.261 4.14.* semver Not specified
CNA Linux Linux unaffected 4.19.224 4.19.* semver Not specified
CNA Linux Linux unaffected 5.4.170 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.90 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.13 5.15.* semver Not specified
CNA Linux Linux unaffected 5.16 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8873140f95d4977bf37e4cf0d5c5e3f6e34cdd3e af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/831de271452b87657fcf8d715ee20519b79caef5 af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/5ec7d18d1813a5bead0b495045606c93873aecbb af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/769d14abd35e0e153b5149c3e1e989a9d719e3ff af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/75799e71df1da11394740b43ae5686646179561d af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
git.kernel.org/stable/c/af6e6e58f7ebf86b4e7201694b1e4f3a62cbc3ec af854a3a-2127-422b-91ae-364da2661108 git.kernel.org Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Legacy QID Mappings

  • 755966 SUSE Enterprise Linux Security Update for the linux kernel (SUSE-SU-2024:0857-1)
  • 755988 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2024:0975-1)
  • 756004 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2024:0926-1)
  • 756005 SUSE Enterprise Linux Security Update for the Linux Kernel (SUSE-SU-2024:0925-1)

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