[Crash-utility] [PATCH] Improve error handling when architecture doesn't match
Bernhard Walle
bwalle at suse.de
Fri Dec 21 15:45:55 UTC 2007
* Dave Anderson <anderson at redhat.com> [2007-12-21 16:00]:
>
> Maybe it should cut down on the initial 32/64-bit verifier
> to check only the ELFMAG and the bytes in the E_IDENT string.
> Then inside of the 32 and 64 bit blocks, first check for
> the architecture and bail out with a "arch-mismatch" error.
> (although in doing so, the e_machine switch statement would
> have to have cases for each arch and its byte-toggled version)
>
> Then the current endian check could be made, and if it
> doesn't match bail out with an "endian" error.
>
> And then for sanity's sake, the remainder of header checks
> could be done, which if we get that far, are pretty much
> guaranteed to never happen.
Sounds sane. What about this:
---
defs.h | 3 +
netdump.c | 119 ++++++++++++++++++++++++++++++++++++++++++++++----------------
tools.c | 9 ++++
3 files changed, 100 insertions(+), 31 deletions(-)
--- a/defs.h
+++ b/defs.h
@@ -3198,7 +3198,8 @@ void stall(ulong);
char *pages_to_size(ulong, char *);
int clean_arg(void);
int empty_list(ulong);
-int machine_type(char *);
+int machine_type(const char *);
+int is_big_endian(void);
void command_not_supported(void);
void option_not_supported(int);
void please_wait(char *);
--- a/netdump.c
+++ b/netdump.c
@@ -36,6 +36,47 @@ static void check_dumpfile_size(char *);
#define ELFREAD 0
#define MIN_PAGE_SIZE (4096)
+#define TOGGLE_ENDIAN_16(val) \
+ (((val >> 8) & 0xff) | ((val << 8) & 0xff00))
+
+
+
+/*
+ * Checks if the machine type of the host matches required_type.
+ * If not, it prints a short error message for the user.
+ */
+static int machine_type_error(const char *required_type)
+{
+ if (machine_type(required_type))
+ return 1;
+ else {
+ fprintf(stderr, "Looks like a valid ELF dump, but host "
+ "architecture (%s) doesn't match dump "
+ "architecture (%s).\n",
+ MACHINE_TYPE, required_type);
+ return 0;
+ }
+}
+
+/*
+ * Returns endianess in a string
+ */
+static const char *endianess_to_string(int big_endian)
+{
+ return big_endian ? "BE" : "LE";
+}
+
+/*
+ * Prints an endian error.
+ */
+static void endian_error(int target_big_endian)
+{
+ fprintf(stderr, "Looks like a valid ELF dump, but host "
+ "endianess (%s) doesn't match target "
+ "endianess (%s)\n",
+ endianess_to_string(is_big_endian()),
+ endianess_to_string(target_big_endian));
+}
/*
* Determine whether a file is a netdump/diskdump/kdump creation,
@@ -99,21 +140,34 @@ is_netdump(char *file, ulong source_quer
* is obviously subject to change.
*/
if (STRNEQ(elf32->e_ident, ELFMAG) &&
- (elf32->e_ident[EI_CLASS] == ELFCLASS32) &&
- (elf32->e_ident[EI_DATA] == ELFDATA2LSB) &&
- (elf32->e_ident[EI_VERSION] == EV_CURRENT) &&
- (elf32->e_type == ET_CORE) &&
- (elf32->e_version == EV_CURRENT) &&
- (elf32->e_phnum >= 2)) {
+ (elf32->e_ident[EI_CLASS] == ELFCLASS32)) {
+
+ /* check arch */
switch (elf32->e_machine)
{
case EM_386:
- if (machine_type("X86"))
- break;
+ case TOGGLE_ENDIAN_16(EM_386):
+ if (!machine_type_error("X86"))
+ goto bailout;
+ break;
default:
goto bailout;
}
+ /* check endianess */
+ if ((elf32->e_ident[EI_DATA] == ELFDATA2LSB && is_big_endian()) ||
+ (elf32->e_ident[EI_DATA] == ELFDATA2MSB && !is_big_endian())) {
+ endian_error(elf32->e_ident[EI_DATA] == ELFDATA2MSB);
+ goto bailout;
+ }
+
+ /* check other ELF headers */
+ if ((elf32->e_ident[EI_VERSION] != EV_CURRENT) ||
+ (elf32->e_type != ET_CORE) ||
+ (elf32->e_version != EV_CURRENT) ||
+ (elf32->e_phnum < 2))
+ goto bailout;
+
load32 = (Elf32_Phdr *)
&header[sizeof(Elf32_Ehdr)+sizeof(Elf32_Phdr)];
size = (size_t)load32->p_offset;
@@ -124,45 +178,52 @@ is_netdump(char *file, ulong source_quer
else
tmp_flags |= NETDUMP_ELF32;
} else if (STRNEQ(elf64->e_ident, ELFMAG) &&
- (elf64->e_ident[EI_CLASS] == ELFCLASS64) &&
- (elf64->e_ident[EI_VERSION] == EV_CURRENT) &&
- (elf64->e_type == ET_CORE) &&
- (elf64->e_version == EV_CURRENT) &&
- (elf64->e_phnum >= 2)) {
+ (elf64->e_ident[EI_CLASS] == ELFCLASS64)) {
+
+ /* check arch */
switch (elf64->e_machine)
{
case EM_IA_64:
- if ((elf64->e_ident[EI_DATA] == ELFDATA2LSB) &&
- machine_type("IA64"))
- break;
- else
+ case TOGGLE_ENDIAN_16(EM_IA_64):
+ if (!machine_type_error("IA64"))
goto bailout;
+ break;
case EM_PPC64:
- if ((elf64->e_ident[EI_DATA] == ELFDATA2MSB) &&
- machine_type("PPC64"))
- break;
- else
+ case TOGGLE_ENDIAN_16(EM_PPC64):
+ if (!machine_type_error("PPC64"))
goto bailout;
+ break;
case EM_X86_64:
- if ((elf64->e_ident[EI_DATA] == ELFDATA2LSB) &&
- machine_type("X86_64"))
- break;
- else
+ case TOGGLE_ENDIAN_16(EM_X86_64):
+ if (!machine_type_error("X86_64"))
goto bailout;
+ break;
case EM_386:
- if ((elf64->e_ident[EI_DATA] == ELFDATA2LSB) &&
- machine_type("X86"))
- break;
- else
+ case TOGGLE_ENDIAN_16(EM_386):
+ if (!machine_type_error("X86"))
goto bailout;
+ break;
default:
goto bailout;
}
+ /* check endianess */
+ if ((elf64->e_ident[EI_DATA] == ELFDATA2LSB && is_big_endian()) ||
+ (elf64->e_ident[EI_DATA] == ELFDATA2MSB && !is_big_endian())) {
+ endian_error(elf64->e_ident[EI_DATA] == ELFDATA2MSB);
+ goto bailout;
+ }
+
+ if ((elf64->e_ident[EI_VERSION] != EV_CURRENT) ||
+ (elf64->e_type != ET_CORE) ||
+ (elf64->e_version != EV_CURRENT) ||
+ (elf64->e_phnum < 2))
+ goto bailout;
+
load64 = (Elf64_Phdr *)
&header[sizeof(Elf64_Ehdr)+sizeof(Elf64_Phdr)];
size = (size_t)load64->p_offset;
--- a/tools.c
+++ b/tools.c
@@ -4518,11 +4518,18 @@ empty_list(ulong list_head_addr)
}
int
-machine_type(char *type)
+machine_type(const char *type)
{
return STREQ(MACHINE_TYPE, type);
}
+int
+is_big_endian(void)
+{
+ unsigned short value = 0xff;
+ return *((unsigned char *)&value) != 0xff;
+}
+
void
command_not_supported()
{
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