On 2023/09/13 9:11, David Mair wrote:
> verify_version() in kernel.c gets a struct syment for linux_banner using
> symbol_search() and uses the value member of the result as the address
> of linux_banner in some cases based on the type member's value in the
> same struct syment. A small number of coredumps with an unhandled type
> ('B' or 'b') for linux_banner result in the address of linux_banner
> being loaded from the actual linux_banner data. This fails because the
> first ulong of the linux_banner ASCII text is treated as a dumped kernel
> address and attempting to access that in the core fails.
>
> Based on a suggestion from Kazu, continue to get the struct syment for
> linux_banner using symbol_search(). Also use get_symbol_type() for
> linux_banner and use the result of that to decide where to get the
> linux_banner address from, disregarding the syment type member. If
> get_symbol_type() reports a TYPE_CODE_ARRAY (and by default with a
> warning) use the syment value member as the linux_banner address. If
> get_symbol_type() reports a TYPE_CODE_PTR read the address of
> linux_banner using get_symbol_data().
>
> The else block doesn't strictly require braced content for a single
> switch statement but braces are included to match style of locally
> similar cases.
>
> Signed-off-by: David Mair <dmair@xxxxxxxx>
Thanks for the patch. Tested ok with various vmcores on hand, and applied.
https://github.com/crash-utility/crash/commit/27f3ccd6c296099206a337c2913f370afcddf1ad
Thanks,
Kazu
> ---
> diff --git a/kernel.c b/kernel.c
> index 988206b..6dcf414 100644
> --- a/kernel.c
> +++ b/kernel.c
> @@ -1076,13 +1076,21 @@ verify_version(void)
>
> if (!(sp = symbol_search("linux_banner")))
> error(FATAL, "linux_banner symbol does not exist?\n");
> - else if ((sp->type == 'R') || (sp->type == 'r') ||
> - (THIS_KERNEL_VERSION >= LINUX(2,6,11) && (sp->type == 'D' ||
> sp->type == 'd')) ||
> - (machine_type("ARM") && sp->type == 'T') ||
> - (machine_type("ARM64")))
> - linux_banner = symbol_value("linux_banner");
> - else
> - get_symbol_data("linux_banner", sizeof(ulong), &linux_banner);
> + else {
> + switch (get_symbol_type("linux_banner", NULL, NULL))
> + {
> + case TYPE_CODE_ARRAY:
> + linux_banner = sp->value;
> + break;
> + case TYPE_CODE_PTR:
> + get_symbol_data("linux_banner", sizeof(ulong), &linux_banner);
> + break;
> + default:
> + error(WARNING, "linux_banner is unknown type\n");
> + linux_banner = sp->value;
> + break;
> + }
> + }
>
> if (!IS_KVADDR(linux_banner))
> error(WARNING, "invalid linux_banner pointer: %lx\n",
>
> --
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