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[patch] Fix crash in svr4_clear_so
- From: Paul Pluzhnikov <ppluzhnikov at google dot com>
- To: gdb-patches at sourceware dot org
- Cc: ppluzhnikov at google dot com
- Date: Tue, 21 May 2013 15:23:49 -0700
- Subject: [patch] Fix crash in svr4_clear_so
Greetings,
Using current trunk, I've got a GDB core dump when I tried to analyze
mis-matched binary and core:
gdb a.out core
GNU gdb (GDB) 7.6.50.20130521-cvs
...
warning: core file may not match specified executable file.
[New LWP 29265]
...
[New LWP 27085]
[New LWP 27052]
warning: Error reading shared library list entry at 0x3b48104f8b480000
Segmentation fault
The actual crash is happening here:
Program received signal SIGSEGV, Segmentation fault.
0x0000000000481376 in svr4_clear_so (so=0xc833490) at ../../src/gdb/solib-svr4.c:974
974 so->lm_info->l_addr_p = 0;
#0 0x0000000000481376 in svr4_clear_so (so=0xc833490) at ../../src/gdb/solib-svr4.c:974
#1 0x0000000000708bc4 in clear_so (so=0xc833490) at ../../src/gdb/solib.c:537
#2 0x0000000000708bef in free_so (so=0xc833490) at ../../src/gdb/solib.c:556
#3 0x00000000006ee328 in do_free_so (arg=0xc833490) at ../../src/gdb/utils.c:492
#4 0x0000000000573474 in do_my_cleanups (pmy_chain=0xc5c1f0 <cleanup_chain>, old_chain=0x35232410) at ../../src/gdb/cleanups.c:155
#5 0x00000000005734e1 in do_cleanups (old_chain=0x35232410) at ../../src/gdb/cleanups.c:177
#6 0x00000000004817e0 in svr4_read_so_list (lm=4271682180386127872, link_ptr_ptr=0x7fff7fc37c58, ignore_first=1) at ../../src/gdb/solib-svr4.c:1195
#7 0x0000000000481b01 in svr4_current_sos () at ../../src/gdb/solib-svr4.c:1311
#8 0x0000000000708eea in update_solib_list (from_tty=0, target=0xc724c0 <core_ops>) at ../../src/gdb/solib.c:674
...
Attached patch fixes the GDB crash.
Ok for trunk?
Thanks,
--
2013-05-21 Paul Pluzhnikov <ppluzhnikov@google.com>
* solib-svr4.c (svr4_free_so): Protect against NULL dereference.
Index: solib-svr4.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-svr4.c,v
retrieving revision 1.177
diff -p -u -r1.177 solib-svr4.c
--- solib-svr4.c 6 May 2013 22:18:38 -0000 1.177
+++ solib-svr4.c 21 May 2013 22:19:09 -0000
@@ -971,7 +971,8 @@ svr4_free_so (struct so_list *so)
static void
svr4_clear_so (struct so_list *so)
{
- so->lm_info->l_addr_p = 0;
+ if (so->lm_info != NULL)
+ so->lm_info->l_addr_p = 0;
}
/* Free so_list built so far (called via cleanup). */