Re: [patch] Fix for PR gdb/10838

[Paul Pluzhnikov <ppluzhnikov@google.com>]

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2009/11/11 Paul Pluzhnikov <ppluzhnikov@google.com>:

> That was fast :-)

Too fast, as it turns out :-(
I didn't test the gdbserver part, but this patch introduced a
gdbserver crash here:

Program terminated with signal 11, Segmentation fault.

#0  0x0000000000408b75 in look_up_one_symbol (name=0x7f6dc44ee3a2
"__nptl_threads_events", addrp=0x7fffcce720c8) at
../../../src/gdb/gdbserver/remote-utils.c:1374
1374      for (sym = proc->symbol_cache; sym; sym = sym->next)

proc is NULL.
Called from:

#0  0x0000000000408b75 in look_up_one_symbol () at
../../../src/gdb/gdbserver/remote-utils.c:1374
#1  0x000000000041ae0e in ps_pglobal_lookup () at
../../../src/gdb/gdbserver/proc-service.c:68
#2  0x00007f6dc44ed60d in td_ta_clear_event () from /lib/libthread_db.so.1
#3  0x000000000041ac8b in thread_db_free (proc=0x6311a0) at
../../../src/gdb/gdbserver/thread-db.c:773
#4  0x0000000000411b44 in linux_remove_process (process=0x6311a0) at
../../../src/gdb/gdbserver/linux-low.c:267

Attached patch fixes that (tested with gdbserver on Linux/x86_64 this time).
The gdb.mi/mi-non-stop-exit.exp test is still failing (regression
since 2009-10-27), but apparently for a different reason.

Thanks,
-- 
Paul Pluzhnikov


2009-11-13  Paul Pluzhnikov  <ppluzhnikov@google.com>

	* proc-service.c (ps_pglobal_lookup): Handle error return
	* remote-utils.c (look_up_one_symbol): Don't crash if the process is gone.

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Index: gdbserver/proc-service.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/proc-service.c,v
retrieving revision 1.14
diff -u -p -u -r1.14 proc-service.c
--- gdbserver/proc-service.c	13 Oct 2009 13:51:21 -0000	1.14
+++ gdbserver/proc-service.c	14 Nov 2009 01:04:48 -0000
@@ -65,7 +65,7 @@ ps_pglobal_lookup (gdb_ps_prochandle_t p
 {
   CORE_ADDR addr;
 
-  if (look_up_one_symbol (name, &addr) == 0)
+  if (look_up_one_symbol (name, &addr) <= 0)
     return PS_NOSYM;
 
   *sym_addr = (psaddr_t) (unsigned long) addr;
Index: gdbserver/remote-utils.c
===================================================================
RCS file: /cvs/src/src/gdb/gdbserver/remote-utils.c,v
retrieving revision 1.68
diff -u -p -u -r1.68 remote-utils.c
--- gdbserver/remote-utils.c	6 Jul 2009 18:31:20 -0000	1.68
+++ gdbserver/remote-utils.c	14 Nov 2009 01:04:48 -0000
@@ -1369,6 +1369,9 @@ look_up_one_symbol (const char *name, CO
   struct process_info *proc;
 
   proc = current_process ();
+  if (proc == NULL)
+    /* Could happen if the process has just exited.  */
+    return -1;
 
   /* Check the cache first.  */
   for (sym = proc->symbol_cache; sym; sym = sym->next)