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authorAndrew Burgess <andrew.burgess@embecosm.com>2021-05-20 09:16:41 +0100
committerAndrew Burgess <andrew.burgess@embecosm.com>2021-05-20 13:35:54 +0100
commit427e4066afd13d1bf52c849849475f536e285d66 (patch)
tree9436dcc8227e05bc1f1be839dcc3d3518c4a0758
parent8baee38bfee176505e6bb541f1df8ec4156b3d46 (diff)
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gdb/bfd: avoid crash when architecture is forced to csky or riscv
I built GDB with `--enable-targets=all`, then started GDB passing it an x86-64 executable, finally I ran 'maint selftest', and observed GDB crash like this: BFD: BFD (GNU Binutils) 2.36.50.20210519 assertion fail ../../src/bfd/hash.c:438 Aborted (core dumped) The problem originates from two locations, for example in csky-dis.c (csky_get_disassembler) where we do this: const char *sec_name = NULL; ... sec_name = get_elf_backend_data (abfd)->obj_attrs_section; if (bfd_get_section_by_name (abfd, sec_name) != NULL) ... We end up in here because during the selftests GDB forces the architecture to be csky, but the BFD being accessed is still of type x86-64. As a result obj_attrs_section returns NULL, which means we end up passing NULL to bfd_get_section_by_name. If we follow the function calls from bfd_get_section_by_name we eventually end up in bfd_hash_hash, which asserts that the string (i.e. the name) is not NULL. The same crash can be reproduced in GDB without using the selftests, for example: (gdb) file x86_64.elf (gdb) start (gdb) set architecture csky (gdb) disassemble main Dump of assembler code for function main: BFD: BFD (GNU Binutils) 2.36.50.20210519 assertion fail ../../src/bfd/hash.c:438 Aborted (core dumped) The fix I propose here is to have bfd_get_section_by_name return NULL if name is ever NULL. For consistency I updated bfd_get_section_by_name_if in the same way, even though I'm not hitting any problems along that code path right now. I looked through the source tree and removed two NULL checks in bfd/dwarf2.c which are no longer needed, its possible that there are additional NULL checks that could be removed, I just didn't find them. bfd/ChangeLog: * section.c (bfd_get_section_by_name): Return NULL if name is NULL. (bfd_get_section_by_name_if): Likewise. * dwarf2.c (read_section): Remove unneeded NULL check. (find_debug_info): Likewise.
-rw-r--r--bfd/ChangeLog8
-rw-r--r--bfd/dwarf2.c12
-rw-r--r--bfd/section.c6
3 files changed, 18 insertions, 8 deletions
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index a389fdf..2ad7803 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,11 @@
+2021-05-20 Andrew Burgess <andrew.burgess@embecosm.com>
+
+ * section.c (bfd_get_section_by_name): Return NULL if name is
+ NULL.
+ (bfd_get_section_by_name_if): Likewise.
+ * dwarf2.c (read_section): Remove unneeded NULL check.
+ (find_debug_info): Likewise.
+
2021-05-19 Nick Clifton <nickc@redhat.com>
* plugin.c (bfd_plugin_open_input): Inform the user if the limit
diff --git a/bfd/dwarf2.c b/bfd/dwarf2.c
index 0a8a557..cf1f1d1 100644
--- a/bfd/dwarf2.c
+++ b/bfd/dwarf2.c
@@ -545,8 +545,7 @@ read_section (bfd * abfd,
if (msec == NULL)
{
section_name = sec->compressed_name;
- if (section_name != NULL)
- msec = bfd_get_section_by_name (abfd, section_name);
+ msec = bfd_get_section_by_name (abfd, section_name);
}
if (msec == NULL)
{
@@ -4226,12 +4225,9 @@ find_debug_info (bfd *abfd, const struct dwarf_debug_section *debug_sections,
return msec;
look = debug_sections[debug_info].compressed_name;
- if (look != NULL)
- {
- msec = bfd_get_section_by_name (abfd, look);
- if (msec != NULL)
- return msec;
- }
+ msec = bfd_get_section_by_name (abfd, look);
+ if (msec != NULL)
+ return msec;
for (msec = abfd->sections; msec != NULL; msec = msec->next)
if (startswith (msec->name, GNU_LINKONCE_INFO))
diff --git a/bfd/section.c b/bfd/section.c
index a353488..6b6aa92 100644
--- a/bfd/section.c
+++ b/bfd/section.c
@@ -898,6 +898,9 @@ bfd_get_section_by_name (bfd *abfd, const char *name)
{
struct section_hash_entry *sh;
+ if (name == NULL)
+ return NULL;
+
sh = section_hash_lookup (&abfd->section_htab, name, false, false);
if (sh != NULL)
return &sh->section;
@@ -1006,6 +1009,9 @@ bfd_get_section_by_name_if (bfd *abfd, const char *name,
struct section_hash_entry *sh;
unsigned long hash;
+ if (name == NULL)
+ return NULL;
+
sh = section_hash_lookup (&abfd->section_htab, name, false, false);
if (sh == NULL)
return NULL;