[Bug tdep/10548] New: Segmentation error due to incomplete initialisation in sparc-tdep.c

["andrew at ultrasoc dot com" <sourceware-bugzilla at sourceware dot org>]

Hi,
I have been trying to use the latest snapshots (20090822) to debug a bare C
program running on a remote SPARC based embedded platform via a JTAG stub and
have experienced a few problems. I believe that I have identified a suitable,
solution to one problem which is as followed.

I run GDB with (-nx):
GNU gdb (GDB) 6.8.50.20090822
?
GDB was configured as "--host=i686-pc-mingw32 --target=sparc-elf"
?

I then connect to my target:
(gdb) tar extended-remote localhost:2222

GDB then segment faults. It looks to me as though on line 1380 of sparc-tdep.c
memory is allocated for the tdep structure and is subsequently not fully
initialised:
tdep = XMALLOC (struct gdbarch_tdep);

At some point later the following parts of the tdep are accessed without being
initialised.
tdep->sparc_psr_type
tdep->sparc_fsr_type

The following functions are used to provide initialisation:
[line 289]
static struct type * sparc_psr_type (struct gdbarch *gdbarch)
[line 312]
static struct type * sparc_fsr_type (struct gdbarch *gdbarch)

However, their initialisation is conditional  ?if (!tdep->sparc_psr_type)? and
because the allocated memory is not cleared this initialisation fails and
subsequent accesses to tdep->sparc_psr_type or tdep->sparc_fsr_type result in a
segmentation error.

I have modified my local code so that on line 1381 the tdep is cleared before
any initialisation takes place.
memset(tdep, 0, sizeof(struct gdbarch_tdep));

I have tested this change and it seems to work as this specific problem goes away.

Kind regards.

-- 
           Summary: Segmentation error due to incomplete initialisation in
                    sparc-tdep.c
           Product: gdb
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tdep
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: andrew at ultrasoc dot com
                CC: gdb-prs at sourceware dot org
 GCC build triplet: i686-pc-mingw32
  GCC host triplet: i686-pc-mingw32
GCC target triplet: sparc-elf


http://sourceware.org/bugzilla/show_bug.cgi?id=10548

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