1. 18 11月, 2006 1 次提交
    • I
      [PATCH] x86_64: stack unwinder crash fix · 0796bdb7
      Ingo Molnar 提交于
      the new dwarf2 unwinder crashes while trying to dump the stack:
      
        Leftover inexact backtrace:
      
        Unable to handle kernel paging request at ffffffff82800000 RIP:
         [<ffffffff8026cf26>] dump_trace+0x35b/0x3d2
        PGD 203027 PUD 205027 PMD 0
        Oops: 0000 [2] PREEMPT SMP
        CPU 0
        Modules linked in:
        Pid: 30, comm: khelper Not tainted 2.6.19-rc6-rt1 #11
        RIP: 0010:[<ffffffff8026cf26>]  [<ffffffff8026cf26>] dump_trace+0x35b/0x3d2
        RSP: 0000:ffff81003fb9d848  EFLAGS: 00010006
        RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
        RDX: 0000000000000000 RSI: ffffffff805b3520 RDI: 0000000000000000
        RBP: ffffffff827ffff9 R08: ffffffff80aad000 R09: 0000000000000005
        R10: ffffffff80aae000 R11: ffffffff8037961b R12: ffff81003fb9d858
        R13: 0000000000000000 R14: ffffffff80598460 R15: ffffffff80ab1fc0
        FS:  0000000000000000(0000) GS:ffffffff806c4200(0000) knlGS:0000000000000000
        CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
        CR2: ffffffff82800000 CR3: 0000000000201000 CR4: 00000000000006e0
      
      this crash happened because it did not sanitize the dwarf2 data it
      got, and got an unaligned stack pointer - which happily walked past
      the process stack (and eventually reached the end of kernel memory
      and pagefaulted there) due to this naive iteration condition:
      
              HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);
      
      note that i386 is alot more conservative when it comes to trusting
      stack pointers:
      
        static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
        {
               return  p > (void *)tinfo &&
                       p < (void *)tinfo + THREAD_SIZE - 3;
        }
      
      but the x86_64 code did not take this bit of i386 code.
      
      The fix is to align the stack pointer.
      Signed-off-by: NIngo Molnar <mingo@elte.hu>
      Cc: Andi Kleen <ak@suse.de>
      Cc: Jan Beulich <jbeulich@novell.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Andrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      0796bdb7
  2. 17 11月, 2006 39 次提交