Subject: CVE-2024-38661: s390/ap: Fix crash in AP internal function modify_bitmap()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

s390/ap: Fix crash in AP internal function modify_bitmap()

A system crash like this

  Failing address: 200000cb7df6f000 TEID: 200000cb7df6f403
  Fault in home space mode while using kernel ASCE.
  AS:00000002d71bc007 R3:00000003fe5b8007 S:000000011a446000 P:000000015660c13d
  Oops: 0038 ilc:3 [#1] PREEMPT SMP
  Modules linked in: mlx5_ib ...
  CPU: 8 PID: 7556 Comm: bash Not tainted 6.9.0-rc7 #8
  Hardware name: IBM 3931 A01 704 (LPAR)
  Krnl PSW : 0704e00180000000 0000014b75e7b606 (ap_parse_bitmap_str+0x10e/0x1f8)
  R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
  Krnl GPRS: 0000000000000001 ffffffffffffffc0 0000000000000001 00000048f96b75d3
  000000cb00000100 ffffffffffffffff ffffffffffffffff 000000cb7df6fce0
  000000cb7df6fce0 00000000ffffffff 000000000000002b 00000048ffffffff
  000003ff9b2dbc80 200000cb7df6fcd8 0000014bffffffc0 000000cb7df6fbc8
  Krnl Code: 0000014b75e7b5fc: a7840047            brc     8,0000014b75e7b68a
  0000014b75e7b600: 18b2                lr      %r11,%r2
  #0000014b75e7b602: a7f4000a            brc     15,0000014b75e7b616
  >0000014b75e7b606: eb22d00000e6        laog    %r2,%r2,0(%r13)
  0000014b75e7b60c: a7680001            lhi     %r6,1
  0000014b75e7b610: 187b                lr      %r7,%r11
  0000014b75e7b612: 84960021            brxh    %r9,%r6,0000014b75e7b654
  0000014b75e7b616: 18e9                lr      %r14,%r9
  Call Trace:
  [<0000014b75e7b606>] ap_parse_bitmap_str+0x10e/0x1f8
  ([<0000014b75e7b5dc>] ap_parse_bitmap_str+0xe4/0x1f8)
  [<0000014b75e7b758>] apmask_store+0x68/0x140
  [<0000014b75679196>] kernfs_fop_write_iter+0x14e/0x1e8
  [<0000014b75598524>] vfs_write+0x1b4/0x448
  [<0000014b7559894c>] ksys_write+0x74/0x100
  [<0000014b7618a440>] __do_syscall+0x268/0x328
  [<0000014b761a3558>] system_call+0x70/0x98
  INFO: lockdep is turned off.
  Last Breaking-Event-Address:
  [<0000014b75e7b636>] ap_parse_bitmap_str+0x13e/0x1f8
  Kernel panic - not syncing: Fatal exception: panic_on_oops

occured when /sys/bus/ap/a[pq]mask was updated with a relative mask value
(like +0x10-0x12,+60,-90) with one of the numeric values exceeding INT_MAX.

The fix is simple: use unsigned long values for the internal variables. The
correct checks are already in place in the function but a simple int for
the internal variables was used with the possibility to overflow.

The Linux kernel CVE team has assigned CVE-2024-38661 to this issue.

Affected and fixed versions
===========================

	Fixed in 4.19.316 with commit 2062e3f1f237
	Fixed in 5.4.278 with commit 7c72af16abf2
	Fixed in 5.10.219 with commit 7360cef95aa1
	Fixed in 5.15.161 with commit 67011123453b
	Fixed in 6.1.94 with commit 8c5f5911c1b1
	Fixed in 6.6.34 with commit 4c0bfb4e867c
	Fixed in 6.9.5 with commit 7dabe54a016d
	Fixed in 6.10 with commit d4f9d5a99a3f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-38661
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	drivers/s390/crypto/ap_bus.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2062e3f1f2374102f8014d7ca286b9aa527bd558
	https://git.kernel.org/stable/c/7c72af16abf2ec7520407098360bbba312289e05
	https://git.kernel.org/stable/c/7360cef95aa1ea2b5efb7b5e2ed32e941664e1f0
	https://git.kernel.org/stable/c/67011123453b91ec03671d40712fa213e94a01b9
	https://git.kernel.org/stable/c/8c5f5911c1b13170d3404eb992c6a0deaa8d81ad
	https://git.kernel.org/stable/c/4c0bfb4e867c1ec6616a5049bd3618021e127056
	https://git.kernel.org/stable/c/7dabe54a016defe11bb2a278cd9f1ff6db3feba6
	https://git.kernel.org/stable/c/d4f9d5a99a3fd1b1c691b7a1a6f8f3f25f4116c9