On Fri, Jun 18, 2010 at 10:11 AM, Prasad Joshi <prasadjoshi124@xxxxxxxxx> wrote: > Hi All, > > I am trying to understand a a kernel oops report. Here are some of the > fields from the report > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000034 > Oops: 0000 [#1] SMP > Pid: 6478, comm: cp Tainted: P 2.6.31.5-127.fc12.x86_64 #1 Inspiron 1525 > RIP: 0010:[<ffffffff810faac1>] [<ffffffff810faac1>] do_sys_open+0x7a/0x10f > CR2: 0000000000000034 > > As I know, when a page fault occurs, the address the program attempted to > access is stored in the CR2 register. So probably the pointer is pointing to > address 0034 and is being access. > > The BUG string is bit confusing, it says NULL pointer dereference at 0034, I > know the address 00034 is not valid but why is it interpreted as NULL > pointer? The NULL pointer as I know should point to address 0. > > Thanks and Regards, > Prasad > Hi Prasad, I think its mostly a case when you have some struct with a pointer as a member which is after 0x34 bytes. Now compiler generate addresses for member variables like (base address of struct) + offset (here 0x34). So in your case, base pointer is NULL and you are trying to access one the members of that struct. Correct me if I am wrong here. -Vinit -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
