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[PATCH] Fix crash when loading a core with unexpected register section size
- From: Antoine Tremblay <antoine dot tremblay at ericsson dot com>
- To: <gdb-patches at sourceware dot org>
- Cc: Antoine Tremblay <antoine dot tremblay at ericsson dot com>
- Date: Thu, 26 Jan 2017 08:17:26 -0500
- Subject: [PATCH] Fix crash when loading a core with unexpected register section size
- Authentication-results: sourceware.org; auth=none
When loading a core without an executable like so:
gdb --core core for example often the gdbarch won't contain the
iterate_over_regset_sections method.
This will generate a call to get_core_register_section with a NULL regset
like at corelow.c:628
get_core_register_section (regcache, NULL, ".reg", 0, 0, "general-purpose", 1);
However a check for REGSET_VARIABLE_SIZE in get_core_register_section
assumes that regset is != NULL thus leading to a crash with this backtrace:
(gdb) bt
#0 0x000000000065907b in get_core_register_section
(regcache=regcache@entry=0x2c26260, regset=regset@entry=0x0,
name=name@entry=0xdbf7b2 ".reg", min_size=min_size@entry=0,
which=which@entry=0, human_name=human_name@entry=0xdbac28
"general-purpose", required=1)
at ../../gdb/corelow.c:542
#1 0x0000000000659b70 in get_core_registers (ops=<optimized out>,
regcache=0x2c26260, regno=<optimized out>) at ../../gdb/corelow.c:628
#2 0x000000000076e5fb in target_fetch_registers
(regcache=regcache@entry=0x2c26260, regno=regno@entry=15) at ../../gdb/target.c:3590
Note that commit: f962539ad23759af4ba8f7eece1946fdc2f5087 introcuded this
issue. Thus releases > 7.8.2 are affected.
This patch fixes this crash by adding a check for regset existence before
running the condition.
gdb/ChangeLog:
* corelow.c (get_core_register_section): Check for regset
existance before checking for REGSET_VARIABLE_SIZE.
---
gdb/corelow.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/gdb/corelow.c b/gdb/corelow.c
index a075d9e..f43f730 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -515,6 +515,7 @@ get_core_register_section (struct regcache *regcache,
struct bfd_section *section;
bfd_size_type size;
char *contents;
+ bool variable_size_section = false;
xfree (section_name);
@@ -534,12 +535,16 @@ get_core_register_section (struct regcache *regcache,
}
size = bfd_section_size (core_bfd, section);
+
+ variable_size_section = (regset != NULL
+ && regset->flags & REGSET_VARIABLE_SIZE);
+
if (size < min_size)
{
warning (_("Section `%s' in core file too small."), section_name);
return;
}
- if (size != min_size && !(regset->flags & REGSET_VARIABLE_SIZE))
+ if (size != min_size && !variable_size_section)
{
warning (_("Unexpected size of section `%s' in core file."),
section_name);
--
2.7.4