Messages in this thread | | | Subject | Re: [PATCH v3] vsprintf: Prevent crash when dereferencing invalid pointers | From | Andy Shevchenko <> | Date | Tue, 03 Apr 2018 14:54:18 +0300 |
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On Tue, 2018-04-03 at 13:46 +0200, Petr Mladek wrote: > On Mon 2018-04-02 17:15:23, Andy Shevchenko wrote: > > On Thu, 2018-03-29 at 16:53 +0200, Petr Mladek wrote: > > > On Fri 2018-03-16 20:19:35, Andy Shevchenko wrote: > > > > On Thu, 2018-03-15 at 16:26 +0100, Petr Mladek wrote: > > > > > On Thu 2018-03-15 15:09:03, Andy Shevchenko wrote: > > > > > > I still think that printing a hex value of the error code is > > > > > > much > > > > > > better > > > > > > than some odd "(efault)". > > > > > > > > > > Do you mean (err:0e)? Google gives rather confusing answers > > > > > for > > > > > this. > > > > > > > > More like "(0xHHHH)" (we have already more than 512 error code > > > > numbers. > > > > > > Hmm, I have never seen the error code in this form. > > > > We have limited space to print it and error numbers currently can be > > up > > to 0xfff (4095). So, I have no better idea how to squeeze them while > > thinking that "(efault)" is much harder to parse in case of error > > pointer. > > But this will not be used instead of address value. It is used in > situations > where we print the information that is stored at the address, for > example, > string, IP address, dentry name.
We have a lot of API functions which returns: -ERR_PTR NULL struct foo *
There is no guarantee that one of that API won't be used as a supplier for printf().
You can't dereference ERR_PTR value, but anything else except the actual error value is worse than value itself...
> > > > Also google gives > > > rather confusing results when searching, for example for > > > "(0x000E)". > > > > It's not primarily for google, though yeah, people would google for > > error messages... > > > > Another question is what the format: decimal versus hex for errors. > > Maybe just "(-DDDDD)"? > > This still looks confusing and google does not help.
...then we have a last option just to print a value as a pointer address.
-- Andy Shevchenko <andriy.shevchenko@linux.intel.com> Intel Finland Oy
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