[PATCH 1/1] Fix segfault in DTC

On Tue, Sep 25, 2012 at 04:51:47PM -0700, Markus Mayer wrote:

On 25/09/2012 16:30, David Gibson wrote:

quoted

On Tue, Sep 25, 2012 at 10:58:09AM -0700, Markus Mayer wrote:

quoted

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