Bug 2324427 (CVE-2024-50161)

Summary:	CVE-2024-50161 kernel: bpf: Check the remaining info_cnt before repeating btf fields
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dfreiber, drow, jburrell, vkumar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2324451
Bug Blocks:

Description OSIDB Bzimport 2024-11-07 17:02:23 UTC

In the Linux kernel, the following vulnerability has been resolved:

bpf: Check the remaining info_cnt before repeating btf fields

When trying to repeat the btf fields for array of nested struct, it
doesn't check the remaining info_cnt. The following splat will be
reported when the value of ret * nelems is greater than BTF_FIELDS_MAX:

  ------------[ cut here ]------------
  UBSAN: array-index-out-of-bounds in ../kernel/bpf/btf.c:3951:49
  index 11 is out of range for type 'btf_field_info [11]'
  CPU: 6 UID: 0 PID: 411 Comm: test_progs ...... 6.11.0-rc4+ #1
  Tainted: [O]=OOT_MODULE
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ...
  Call Trace:
   <TASK>
   dump_stack_lvl+0x57/0x70
   dump_stack+0x10/0x20
   ubsan_epilogue+0x9/0x40
   __ubsan_handle_out_of_bounds+0x6f/0x80
   ? kallsyms_lookup_name+0x48/0xb0
   btf_parse_fields+0x992/0xce0
   map_create+0x591/0x770
   __sys_bpf+0x229/0x2410
   __x64_sys_bpf+0x1f/0x30
   x64_sys_call+0x199/0x9f0
   do_syscall_64+0x3b/0xc0
   entry_SYSCALL_64_after_hwframe+0x4b/0x53
  RIP: 0033:0x7fea56f2cc5d
  ......
   </TASK>
  ---[ end trace ]---

Fix it by checking the remaining info_cnt in btf_repeat_fields() before
repeating the btf fields.

Comment 1 Robb Gatica 2024-11-07 19:37:53 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024110747-CVE-2024-50161-1313@gregkh/T