Find the answer to your Linux question:
Results 1 to 2 of 2
Enjoy an ad free experience by logging in. Not a member yet? Register.
  1. #1

    Null pointer at "data16" instruction??

    I had a panic in smbd:

    crash> log | grep -A 1 NULL
    (U1)(MSG-KERN-00009):[1272501291.384650] Unable to handle kernel NULL pointer dereference at 0000000000000010 RIP:
    (E1)[1272501291.486584] <ffffffff802570b9>{copy_user_generic+169}

    "Great" I thought to myself, "a samba bug"..but then I looked at the panic, and the actual instruction is "data16":
    0xffffffff802570b2 <copy_user_generic+162>:     mov    %edx,%ecx
    0xffffffff802570b4 <copy_user_generic+164>:     and    $0x7,%ecx
    0xffffffff802570b7 <copy_user_generic+167>:     je     0xffffffff802570ce <copy_user_generic+190>
    0xffffffff802570b9 <copy_user_generic+169>:     data16
    0xffffffff802570ba <copy_user_generic+170>:     data16
    0xffffffff802570bb <copy_user_generic+171>:     data16
    0xffffffff802570bc <copy_user_generic+172>:     nop
    0xffffffff802570bd <copy_user_generic+173>:     data16
    0xffffffff802570be <copy_user_generic+174>:     data16
    That doesn't make any sense to me, data16 shouldn't do any memory reference (right?), nothing else seems obviously funky...any ideas what might have happened here?

  2. #2
    Linux Guru Rubberman's Avatar
    Join Date
    Apr 2009
    I can be found either 40 miles west of Chicago, in Chicago, or in a galaxy far, far away.
    I'd also check +190 which is the target address of the jump (je) at +167. Sometimes these dumps show the address right after where the error really occurred. Anyway, just a SWAG...
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts