Re: [patch] nto target: fix null pointer dereference

Aleksandar Ristovski
2008-08-14T20:46:30Z

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Ulrich Weigand wrote:
>
> ... you might want to cache the address you've computed once

Changed accordingly, new patch attached.

Thanks,

Aleksandar

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2008-08-14 Aleksandar Ristovski <aristovski@qnx.com>

* nto-tdep.c (lm_info): Updated struct lm_info definition from
solib-svr4.c
(LM_ADDR): Use l_addr if available; if not, use link map and set l_addr.

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Index: gdb/nto-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/nto-tdep.c,v
retrieving revision 1.25
diff -u -p -r1.25 nto-tdep.c
--- gdb/nto-tdep.c 23 Jul 2008 13:36:00 -0000 1.25
+++ gdb/nto-tdep.c 14 Aug 2008 20:37:20 -0000
@@ -253,21 +253,39 @@ nto_parse_redirection (char *pargv[], co
solib-svr4.c to support nto_relocate_section_addresses
which is different from the svr4 version. */

+/* Link map info to include in an allocated so_list entry */
+
struct lm_info
-{
- /* Pointer to copy of link map from inferior. The type is char *
- rather than void *, so that we may use byte offsets to find the
- various fields without the need for a cast. */
- char *lm;
-};
+ {
+ /* Pointer to copy of link map from inferior. The type is char *
+ rather than void *, so that we may use byte offsets to find the
+ various fields without the need for a cast. */
+ gdb_byte *lm;
+
+ /* Amount by which addresses in the binary should be relocated to
+ match the inferior. This could most often be taken directly
+ from lm, but when prelinking is involved and the prelink base
+ address changes, we may need a different offset, we want to
+ warn about the difference and compute it only once. */
+ CORE_ADDR l_addr;
+
+ /* The target location of lm. */
+ CORE_ADDR lm_addr;
+ };
+

static CORE_ADDR
LM_ADDR (struct so_list *so)
{
- struct link_map_offsets *lmo = nto_fetch_link_map_offsets ();
+ if (so->lm_info->l_addr == (CORE_ADDR)-1)
+ {
+ struct link_map_offsets *lmo = nto_fetch_link_map_offsets ();

- return extract_typed_address (so->lm_info->lm + lmo->l_addr_offset,
- builtin_type_void_data_ptr);
+ so->lm_info->l_addr =
+ extract_typed_address (so->lm_info->lm + lmo->l_addr_offset,
+ builtin_type_void_data_ptr);
+ }
+ return so->lm_info->l_addr;
}

static CORE_ADDR