[PATCH 1/1] Fix segfault in DTC

[David Gibson]

On Tue, Sep 25, 2012 at 04:51:47PM -0700, Markus Mayer wrote:
> On 25/09/2012 16:30, David Gibson wrote:
> >On Tue, Sep 25, 2012 at 10:58:09AM -0700, Markus Mayer wrote:
> >>Prior to this change, an empty input file would cause a segfault, because
> >>yylloc had never been initialized. There was never any characters for the
> >>lexer to match, so YY_USER_ACTION was never executed before the parse error
> >>was detected.
> >>
> >>When the parser printed the error message, it tried to include the name of
> >>the file, but the structure holding the file name (yylloc.file, referenced
> >>as pos->file) had never been initialized.
> >>
> >>Without the fix:
> >>
> >>$ ./dtc /dev/null
> >>DTC: dts->dts  on file "/dev/null"
> >>Segmentation fault (core dumped)
> >>
> >>$ gdb dtc core
> >>Program terminated with signal 11, Segmentation fault.
> >>     at scripts/dtc/srcpos.c:194
> >>194			fname = pos->file->name;
> >>(gdb) bt
> >>     at scripts/dtc/srcpos.c:194
> >>     fmt=0x40d769 "%s", va=0x7fffbf027148) at scripts/dtc/srcpos.c:220
> >>     at scripts/dtc/dtc-parser.tab.c:1920
> >>     at scripts/dtc/treesource.c:38
> >>     at scripts/dtc/dtc.c:203
> >>(gdb) p *pos
> >>$1 = {first_line = 0, first_column = 0, last_line = 0, last_column = 0,
> >>   file = 0x0}
> >
> >Which dtc version did you observe this with?  I'm unable to reproduce
> >the SEGV with current git.
> 
> That was
> 
> $ cat version_gen.h
> #define DTC_VERSION "DTC 1.2.0-g37c0b6a0"
> 
> from
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git. In
> other words, the DTC used by the Linux 3.6-rc series.

Ah, ok.  Patches to dtc should be made against the upstream version at
git://git.jdl.com/software/dtc.git.  In this case the bug was already
fixed there, in commit a6e6c60e3a97a6b3a033cd052bb3740fd53cbf4c.

I think we're overdue to update the kernel copy of dtc from upstream.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson