[rtems commit] libdl: Fix loading symbol that reference unknown sections.
Chris Johns
chrisj at rtems.org
Mon May 13 22:57:13 UTC 2019
Module: rtems
Branch: master
Commit: 74883be5d4b5fa166179d6003032f6eac2e0f544
Changeset: http://git.rtems.org/rtems/commit/?id=74883be5d4b5fa166179d6003032f6eac2e0f544
Author: Chris Johns <chrisj at rtems.org>
Date: Mon May 13 10:46:45 2019 +1000
libdl: Fix loading symbol that reference unknown sections.
- Make the symbol parsing and loading stage match.
- Check for possible overflow of the tables when loading.
Closes #3746
---
cpukit/libdl/rtl-elf.c | 215 ++++++++++++++++++++++++++++++++++++-------------
1 file changed, 159 insertions(+), 56 deletions(-)
diff --git a/cpukit/libdl/rtl-elf.c b/cpukit/libdl/rtl-elf.c
index 0fa639f..3b44f8c 100644
--- a/cpukit/libdl/rtl-elf.c
+++ b/cpukit/libdl/rtl-elf.c
@@ -51,6 +51,62 @@ static rtems_rtl_loader_format elf_sig =
.flags = RTEMS_RTL_FMT_ELF
};
+static const char*
+rtems_rtl_elf_sym_type_label (Elf_Byte st_info)
+{
+ const char* label;
+ switch (ELF_ST_TYPE (st_info))
+ {
+ case STT_NOTYPE:
+ label = "STT_NOTYPE";
+ break;
+ case STT_OBJECT:
+ label = "STT_OBJECT";
+ break;
+ case STT_FUNC:
+ label = "STT_FUNC";
+ break;
+ case STT_SECTION:
+ label = "STT_SECTION";
+ break;
+ case STT_FILE:
+ label = "STT_FILE";
+ break;
+ case STT_COMMON:
+ label = "STT_COMMON";
+ break;
+ case STT_TLS:
+ label = "STT_TLS";
+ break;
+ default:
+ label = "unknown";
+ break;
+ }
+ return label;
+}
+
+static const char*
+rtems_rtl_elf_sym_bind_label (Elf_Byte st_info)
+{
+ const char* label;
+ switch (ELF_ST_BIND (st_info))
+ {
+ case STB_LOCAL:
+ label = "STB_LOCAL";
+ break;
+ case STB_GLOBAL:
+ label = "STB_GLOBAL";
+ break;
+ case STB_WEAK:
+ label = "STB_WEAK";
+ break;
+ default:
+ label = "unknown";
+ break;
+ }
+ return label;
+}
+
static bool
rtems_rtl_elf_machine_check (Elf_Ehdr* ehdr)
{
@@ -842,11 +898,13 @@ rtems_rtl_elf_symbols_load (rtems_rtl_obj* obj,
* we need to make sure there is a valid seciton.
*/
if (rtems_rtl_trace (RTEMS_RTL_TRACE_SYMBOL))
- printf ("rtl: sym:elf:%-4d name:%-4d: %-20s: bind:%-2d " \
- "type:%-2d sect:%-5d size:%-5d value:%d\n",
+ printf ("rtl: sym:elf:%-4d name:%-4d: %-20s: bind:%-2d:%-12s " \
+ "type:%-2d:%-10s sect:%-5d size:%-5d value:%d\n",
sym, (int) symbol.st_name, name,
(int) ELF_ST_BIND (symbol.st_info),
+ rtems_rtl_elf_sym_bind_label (symbol.st_info),
(int) ELF_ST_TYPE (symbol.st_info),
+ rtems_rtl_elf_sym_type_label (symbol.st_info),
symbol.st_shndx,
(int) symbol.st_size,
(int) symbol.st_value);
@@ -998,68 +1056,113 @@ rtems_rtl_elf_symbols_load (rtems_rtl_obj* obj,
(ELF_ST_BIND (symbol.st_info) == STB_WEAK) ||
(ELF_ST_BIND (symbol.st_info) == STB_LOCAL)))
{
- rtems_rtl_obj_sym* osym;
- char* string;
- Elf_Word value;
- const char* name;
-
- off = obj->ooffset + strtab->offset + symbol.st_name;
- len = RTEMS_RTL_ELF_STRING_MAX;
-
- if (!rtems_rtl_obj_cache_read (strings, fd, off, (void**) &name, &len))
- return false;
+ rtems_rtl_obj_sect* symsect;
/*
- * If a duplicate forget it.
+ * There needs to be a valid section for the symbol.
*/
- if (rtems_rtl_symbol_global_find (name))
- continue;
+ symsect = rtems_rtl_obj_find_section_by_index (obj, symbol.st_shndx);
- if ((ELF_ST_BIND (symbol.st_info) == STB_GLOBAL) ||
- (ELF_ST_BIND (symbol.st_info) == STB_WEAK))
- {
- osym = gsym;
- string = gstring;
- gstring += strlen (name) + 1;
- ++gsym;
- }
- else
+ if (symsect != NULL)
{
- osym = lsym;
- string = lstring;
- lstring += strlen (name) + 1;
- ++lsym;
- }
+ rtems_rtl_obj_sym* osym;
+ char* string;
+ Elf_Word value;
+ const char* name;
- /*
- * Allocate any common symbols in the common section.
- */
- if (symbol.st_shndx == SHN_COMMON)
- {
- size_t value_off = rtems_rtl_obj_align (common_offset,
- symbol.st_value);
- common_offset = value_off + symbol.st_size;
- value = value_off;
- }
- else
- {
- value = symbol.st_value;
- }
+ off = obj->ooffset + strtab->offset + symbol.st_name;
+ len = RTEMS_RTL_ELF_STRING_MAX;
- rtems_chain_set_off_chain (&osym->node);
- memcpy (string, name, strlen (name) + 1);
- osym->name = string;
- osym->value = (uint8_t*) value;
- osym->data = symbol.st_shndx;
+ if (!rtems_rtl_obj_cache_read (strings, fd, off, (void**) &name, &len))
+ return false;
- if (rtems_rtl_trace (RTEMS_RTL_TRACE_SYMBOL))
- printf ("rtl: sym:add:%-4d name:%-4d: %-20s: bind:%-2d " \
- "type:%-2d val:%-8p sect:%-3d size:%d\n",
- sym, (int) symbol.st_name, osym->name,
- (int) ELF_ST_BIND (symbol.st_info),
- (int) ELF_ST_TYPE (symbol.st_info),
- osym->value, symbol.st_shndx,
- (int) symbol.st_size);
+ /*
+ * If a duplicate forget it.
+ */
+ if (rtems_rtl_symbol_global_find (name))
+ continue;
+
+ if ((ELF_ST_BIND (symbol.st_info) == STB_GLOBAL) ||
+ (ELF_ST_BIND (symbol.st_info) == STB_WEAK))
+ {
+ size_t slen = strlen (name) + 1;
+ if ((gstring + slen) > (char*) obj->global_table + obj->global_size)
+ string = NULL;
+ else
+ {
+ osym = gsym;
+ string = gstring;
+ gstring += slen + 1;
+ ++gsym;
+ }
+ }
+ else
+ {
+ size_t slen = strlen (name) + 1;
+ if ((lstring + slen) > (char*) obj->local_table + obj->local_size)
+ string = NULL;
+ else
+ {
+ osym = lsym;
+ string = lstring;
+ lstring += slen + 1;
+ ++lsym;
+ }
+ }
+
+ /*
+ * See if the loading has overflowed the allocated tables.
+ */
+ if (string == NULL)
+ {
+ if (obj->local_syms)
+ {
+ rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_SYMBOL, obj->local_table);
+ obj->local_table = NULL;
+ obj->local_size = 0;
+ obj->local_syms = 0;
+ }
+ if (obj->global_syms)
+ {
+ rtems_rtl_alloc_del (RTEMS_RTL_ALLOC_SYMBOL, obj->global_table);
+ obj->global_table = NULL;
+ obj->global_syms = 0;
+ obj->global_size = 0;
+ }
+ rtems_rtl_set_error (ENOMEM, "syms overlow, parsing/loading size mismatch");
+ return false;
+ }
+
+ /*
+ * Allocate any common symbols in the common section.
+ */
+ if (symbol.st_shndx == SHN_COMMON)
+ {
+ size_t value_off = rtems_rtl_obj_align (common_offset,
+ symbol.st_value);
+ common_offset = value_off + symbol.st_size;
+ value = value_off;
+ }
+ else
+ {
+ value = symbol.st_value;
+ }
+
+ rtems_chain_set_off_chain (&osym->node);
+ memcpy (string, name, strlen (name) + 1);
+ osym->name = string;
+ osym->value = (uint8_t*) value;
+ osym->data = symbol.st_shndx;
+
+ if (rtems_rtl_trace (RTEMS_RTL_TRACE_SYMBOL))
+ printf ("rtl: sym:add:%-4d name:%-4d: %-20s: bind:%-2d " \
+ "type:%-2d val:%-8p sect:%-3d size:%d\n",
+ sym, (int) symbol.st_name, osym->name,
+ (int) ELF_ST_BIND (symbol.st_info),
+ (int) ELF_ST_TYPE (symbol.st_info),
+ osym->value, symbol.st_shndx,
+ (int) symbol.st_size);
+ }
}
}
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