[Crash-utility] [PATCH] Improve error handling when architecture doesn't match
Dave Anderson
anderson at redhat.com
Fri Dec 21 16:20:45 UTC 2007
Bernhard Walle wrote:
> * 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:
>
Looks reasonable.
BTW, since is_netdump() gets called twice, first
directly and then via is_kdump(), do the error
messages get printed twice?
>
> ---
> 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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