tree f07597f86baea4f27d08bb4c47a1a25751da80a7
parent ac68ff92ae20f7447f7af6c154a95f528df46851
author Greg Kurz <groug@kaod.org> 1535623319 +0200
committer David Gibson <david@gibson.dropbear.id.au> 1535678013 +1000

Kill bogus TYPE_BLOB marker type

Since commit 32b9c6130762 "Preserve datatype markers when emitting dts
format", we no longer try to guess the value type. Instead, we reuse
the type of the datatype markers when they are present, if the type
is either TYPE_UINT* or TYPE_STRING.

This causes 'dtc -I fs' to crash:

Starting program: /root/dtc -q -f -O dts -I fs /proc/device-tree
/dts-v1/;

/ {

Program received signal SIGSEGV, Segmentation fault.
__strlen_power8 () at ../sysdeps/powerpc/powerpc64/power8/strlen.S:47
47              ld      r12,0(r4)     /* Load doubleword from memory.  */
(gdb) bt
#0  __strlen_power8 () at ../sysdeps/powerpc/powerpc64/power8/strlen.S:47
#1  0x00007ffff7de3d10 in __GI__IO_fputs (str=<optimized out>,
    fp=<optimized out>) at iofputs.c:33
#2  0x000000001000c7a0 in write_propval (prop=0x100525e0,
    f=0x7ffff7f718a0 <_IO_2_1_stdout_>) at treesource.c:245

The offending line is:

                fprintf(f, "%s", delim_start[emit_type]);

where emit_type is TYPE_BLOB and:

static const char *delim_start[] = {
        [TYPE_UINT8] = "[",
        [TYPE_UINT16] = "/bits/ 16 <",
        [TYPE_UINT32] = "<",
        [TYPE_UINT64] = "/bits/ 64 <",
        [TYPE_STRING] = "",
};

/* Data blobs */
enum markertype {
        TYPE_NONE,
        REF_PHANDLE,
        REF_PATH,
        LABEL,
        TYPE_UINT8,
        TYPE_UINT16,
        TYPE_UINT32,
        TYPE_UINT64,
        TYPE_BLOB,
        TYPE_STRING,
};

Because TYPE_BLOB < TYPE_STRING and delim_start[] is a static array,
delim_start[emit_type] is 0x0. The glibc usually prints out "(null)"
when one passes 0x0 to %s, but it seems to call fputs() internally if
the format is exactly "%s", hence the crash.

TYPE_BLOB basically means the data comes from a file and we don't know
its type. We don't care for the former, and the latter is TYPE_NONE.

So let's drop TYPE_BLOB completely and use TYPE_NONE instead when reading
the file. Then, try to guess the data type at emission time, like the
code already does for refs and labels.

Instead of adding yet another check for TYPE_NONE, an helper is introduced
to check if the data marker has type information, ie, >= TYPE_UINT8.

Fixes: 32b9c61307629ac76c6ac0bead6f926d579b3d2c
Suggested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>