KASSERT(val != 0) not triggering in linux_errno.c reading outside of array

[Hans Petter Selasky]

On 2020-11-03 11:17, xtouqh at hotmail.com wrote:
> Hans Petter Selasky wrote:
>> Hi,
>>
>> Should:
>>
>>          for (i = 1; i < sizeof(linux_errtbl); i++) {
>>
>> Be:
>>
>>          for (i = 1; i < sizeof(linux_errtbl)/sizeof(linux_errtbl[0]); 
>> i++) {
>>
>>
>> Or:
>>
>>          for (i = 1; i < (int)nitems(linux_errtbl); i++) {
> 
> That's right, and I added the same comment in the review.  My question 
> is different though -- with the issue present, KASSERT() should have 
> triggered (there are 0 values with incorrect indexes, added printf() 
> confirms that) exposing the bug, but it does not -- WHY? -- I just want 
> to understand what's going on.

Hi,

You would need to run kgdb to dump the content of linux_errtbl and 
beyond to see what data is there.

If the linux_errtbl is in the .text section then likely some other table 
follows after it, likely with non-zero data, so the KASSERT() doesn't 
trigger :-(


--HPS