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

JIRA: https://issues.redhat.com/browse/RHEL-86670

commit d4f9d5a
Author: Harald Freudenberger <[email protected]>
Date:   Mon May 13 14:49:13 2024 +0200

    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.

    Reported-by: Marc Hartmayer <[email protected]>
    Signed-off-by: Harald Freudenberger <[email protected]>
    Tested-by: Marc Hartmayer <[email protected]>
    Reviewed-by: Holger Dengler <[email protected]>
    Cc: <[email protected]>
    Signed-off-by: Heiko Carstens <[email protected]>

Signed-off-by: Thomas Huth <[email protected]>

Author: huth

drivers/s390/crypto/ap_bus.c

@@ -1111,7 +1111,7 @@ EXPORT_SYMBOL(ap_hex2bitmap);
  */
 static int modify_bitmap(const char *str, unsigned long *bitmap, int bits)
 {
-	int a, i, z;
+	unsigned long a, i, z;
 	char *np, sign;
 
 	/* bits needs to be a multiple of 8 */