CVE-2023-53296 - sctp: check send stream number after wait_for_sndbuf

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MEDIUM

sctp: check send stream number after wait_for_sndbuf

Published Sep 16, 2025

5.5

MEDIUM

CVSS 3.1

EPSS 0.15%

Description

This patch fixes a corner case where the asoc out stream count may change after wait_for_sndbuf.

When the main thread in the client starts a connection, if its out stream count is set to N while the in stream count in the server is set to N - 2, another thread in the client keeps sending the msgs with stream number N - 1, and waits for sndbuf before processing INIT_ACK.

However, after processing INIT_ACK, the out stream count in the client is shrunk to N - 2, the same to the in stream count in the server. The crash occurs when the thread waiting for sndbuf is awake and sends the msg in a non-existing stream(N - 1), the call trace is as below:

KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] Call Trace: <TASK> sctp_cmd_send_msg net/sctp/sm_sideeffect.c:1114 [inline] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1777 [inline] sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline] sctp_do_sm+0x197d/0x5310 net/sctp/sm_sideeffect.c:1170 sctp_primitive_SEND+0x9f/0xc0 net/sctp/primitive.c:163 sctp_sendmsg_to_asoc+0x10eb/0x1a30 net/sctp/socket.c:1868 sctp_sendmsg+0x8d4/0x1d90 net/sctp/socket.c:2026 inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:825 sock_sendmsg_nosec net/socket.c:722 [inline] sock_sendmsg+0xde/0x190 net/socket.c:745

The fix is to add an unlikely check for the send stream number after the thread wakes up from the wait_for_sndbuf.

Affected products

Vendor Linux Product Linux Default
unaffected
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
- Version
  
  Status
  affected
  Constraints
Vendor Linux Product Linux Default
affected
- Version
  4.15
  Status
  affected
  Constraints
  -
- Version
  0
  Status
  unaffected
  Constraints
  <4.15
- Version
  4.19.281
  Status
  unaffected
  Constraints
  <=4.19.*
- Version
  5.10.178
  Status
  unaffected
  Constraints
  <=5.10.*
- Version
  5.15.107
  Status
  unaffected
  Constraints
  <=5.15.*
- Version
  5.4.241
  Status
  unaffected
  Constraints
  <=5.4.*
- Version
  6.1.24
  Status
  unaffected
  Constraints
  <=6.1.*
- Version
  6.2.11
  Status
  unaffected
  Constraints
  <=6.2.*
- Version
  6.3
  Status
  unaffected
  Constraints
  <=*

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Linux

unaffected

Version	Status	Constraints
	affected
	affected
	affected
	affected
	affected
	affected
	affected

Linux

affected

Version	Status	Constraints
4.15	affected	-
0	unaffected	<4.15
4.19.281	unaffected	<=4.19.*
5.10.178	unaffected	<=5.10.*
5.15.107	unaffected	<=5.15.*
5.4.241	unaffected	<=5.4.*
6.1.24	unaffected	<=6.1.*
6.2.11	unaffected	<=6.2.*
6.3	unaffected	<=*

Red Hat Enterprise Linux 8

kernel-0:4.18.0-513.5.1.el8_9

Fixed · RHSA-2023:7077
Red Hat Enterprise Linux 8.8 Extended Update Support

kernel-0:4.18.0-477.43.1.el8_8

Fixed · RHSA-2024:0575
Red Hat Enterprise Linux 10

kernel

Not affected
Red Hat Enterprise Linux 6

kernel

Out of support scope
Red Hat Enterprise Linux 7

kernel

Out of support scope
Red Hat Enterprise Linux 7

kernel-rt

Out of support scope
Red Hat Enterprise Linux 8

kernel-rt

Out of support scope
Red Hat Enterprise Linux 9

kernel

Fix deferred
Red Hat Enterprise Linux 9

kernel-rt

Fix deferred

Product	Package	State	Advisory
Red Hat Enterprise Linux 8	kernel-0:4.18.0-513.5.1.el8_9	Fixed	RHSA-2023:7077
Red Hat Enterprise Linux 8.8 Extended Update Support	kernel-0:4.18.0-477.43.1.el8_8	Fixed	RHSA-2024:0575
Red Hat Enterprise Linux 10	kernel	Not affected	n/a
Red Hat Enterprise Linux 6	kernel	Out of support scope	n/a
Red Hat Enterprise Linux 7	kernel	Out of support scope	n/a
Red Hat Enterprise Linux 7	kernel-rt	Out of support scope	n/a
Red Hat Enterprise Linux 8	kernel-rt	Out of support scope	n/a
Red Hat Enterprise Linux 9	kernel	Fix deferred	n/a
Red Hat Enterprise Linux 9	kernel-rt	Fix deferred	n/a

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-476

NULL Pointer Dereference

References (13)

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2023-53296		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2395682		Issue Tracking
https://euvd.enisa.europa.eu/vulnerability/EUVD-2023-59893		Advisory
https://git.kernel.org/stable/c/0443fff49d6352160c200064156c25898bd9f58c		Patch
https://git.kernel.org/stable/c/2584024b23552c00d95b50255e47bd18d306d31a		Patch
https://git.kernel.org/stable/c/667eb99cf7c15fe5b0ecefe75cf658e20ef20c9f		Patch
https://git.kernel.org/stable/c/9346a1a21142357972a6f466ba6275ddc54b04ac		Patch
https://git.kernel.org/stable/c/a615e7270318fa0b98bf1ff38daf6cf52d840312		Patch
https://git.kernel.org/stable/c/b4b6dfad41aaae9e36e44327b18d5cf4b20dd2ce		Patch
https://git.kernel.org/stable/c/d2128636b303aa9cf065055402ee6697409a8837		Patch
https://lore.kernel.org/linux-cve-announce/2025091627-CVE-2023-53296-9947@gregkh/T
https://nvd.nist.gov/vuln/detail/CVE-2023-53296
https://www.cve.org/CVERecord?id=CVE-2023-53296