src/patches/suse-2.6.27.25/patches.fixes/kdb-oops-panic.diff

   1 From: Bernhard Walle <bwalle@suse.de>
   2 Subject: [PATCH] Fix NULL pointer dereference when regs == NULL
   3 References: bnc#439007
   4
   5 This patch fixes following problem:
   6
   7 When panic() in user context, for example by
   8
   9     # modprobe crasher call_panic
  10
  11 then KDB crashed in kdba_getpc() once because regs was not checked for being
  12 NULL:
  13
  14     Entering kdb (current=0xffff880036c747c0, pid 4420) on processor 1 Oops: <NULL>
  15     BUG: unable to handle kernel NULL pointer dereference at 0000000000000080
  16     IP: [<ffffffff80415ee2>] kdba_getpc+0x0/0x8
  17     PGD 379f4067 PUD 39997067 PMD 0
  18     Oops: 0000 [1] SMP
  19     last sysfs file: /sys/devices/pci0000:00/0000:00:1c.5/0000:06:00.0/irq
  20     kdb: Debugger re-entered on cpu 1, new reason = 5
  21          Not executing a kdb command
  22          No longjmp available for recovery
  23          Cannot recover, allowing event to proceed
  24
  25 Even if that has ieen fixed, then kdba_dumpregs() crashed because
  26 the return value of kdba_getpc() was assumed to be non-NULL.
  27
  28 This patch simply ports the error handling from its 32 bit counterpart
  29 implementation. After applying that fix, the test mentioned above succeeds:
  30
  31     Entering kdb (current=0xffff8800355fc480, pid 7564) on processor 1 Oops: <NULL>
  32     due to oops @ 0x0
  33     kdba_dumpregs: pt_regs not available, use bt* or pid to select a different task
  34     [1]kdb>
  35
  36
  37 Signed-off-by: Bernhard Walle <bwalle@suse.de>
  38
  39 ---
  40  arch/x86/kdb/kdbasupport_64.c |    7 ++++++-
  41  1 file changed, 6 insertions(+), 1 deletion(-)
  42
  43 --- a/arch/x86/kdb/kdbasupport_64.c
  44 +++ b/arch/x86/kdb/kdbasupport_64.c
  45 @@ -501,6 +501,11 @@ kdba_dumpregs(struct pt_regs *regs,
  46                 struct kdbregs *rlp;
  47                 kdb_machreg_t contents;
  48
  49 +               if (!regs) {
  50 +                       kdb_printf("%s: pt_regs not available, use bt* or pid to select a different task\n", __FUNCTION__);
  51 +                       return KDB_BADREG;
  52 +               }
  53 +
  54                 for (i=0, rlp=kdbreglist; i<nkdbreglist; i++,rlp++) {
  55                         kdb_printf("%8s = ", rlp->reg_name);
  56                         kdba_getregcontents(rlp->reg_name, regs, &contents);
  57 @@ -554,7 +559,7 @@ EXPORT_SYMBOL(kdba_dumpregs);
  58  kdb_machreg_t
  59  kdba_getpc(struct pt_regs *regs)
  60  {
  61 -       return regs->ip;
  62 +       return regs ? regs->ip : 0;
  63  }
  64
  65  int