From 99e729bd40fb3272fa4b0140839d5e957b58588a Mon Sep 17 00:00:00 2001 From: Sergei Trofimovich Date: Thu, 29 Apr 2021 22:53:48 -0700 Subject: ia64: module: fix symbolizer crash on fdescr Noticed failure as a crash on ia64 when tried to symbolize all backtraces collected by page_owner=on: $ cat /sys/kernel/debug/page_owner CPU: 1 PID: 2074 Comm: cat Not tainted 5.12.0-rc4 #226 Hardware name: hp server rx3600, BIOS 04.03 04/08/2008 ip is at dereference_module_function_descriptor+0x41/0x100 Crash happens at dereference_module_function_descriptor() due to use-after-free when dereferencing ".opd" section header. All section headers are already freed after module is laoded successfully. To keep symbolizer working the change stores ".opd" address and size after module is relocated to a new place and before section headers are discarded. To make similar errors less obscure module_finalize() now zeroes out all variables relevant to module loading only. Link: https://lkml.kernel.org/r/20210403074803.3309096-1-slyfox@gentoo.org Signed-off-by: Sergei Trofimovich Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/ia64/kernel/module.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) (limited to 'arch/ia64/kernel') diff --git a/arch/ia64/kernel/module.c b/arch/ia64/kernel/module.c index 00a496cb346f..2cba53c1da82 100644 --- a/arch/ia64/kernel/module.c +++ b/arch/ia64/kernel/module.c @@ -905,9 +905,31 @@ register_unwind_table (struct module *mod) int module_finalize (const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *mod) { + struct mod_arch_specific *mas = &mod->arch; + DEBUGP("%s: init: entry=%p\n", __func__, mod->init); - if (mod->arch.unwind) + if (mas->unwind) register_unwind_table(mod); + + /* + * ".opd" was already relocated to the final destination. Store + * it's address for use in symbolizer. + */ + mas->opd_addr = (void *)mas->opd->sh_addr; + mas->opd_size = mas->opd->sh_size; + + /* + * Module relocation was already done at this point. Section + * headers are about to be deleted. Wipe out load-time context. + */ + mas->core_plt = NULL; + mas->init_plt = NULL; + mas->got = NULL; + mas->opd = NULL; + mas->unwind = NULL; + mas->gp = 0; + mas->next_got_entry = 0; + return 0; } @@ -926,10 +948,9 @@ module_arch_cleanup (struct module *mod) void *dereference_module_function_descriptor(struct module *mod, void *ptr) { - Elf64_Shdr *opd = mod->arch.opd; + struct mod_arch_specific *mas = &mod->arch; - if (ptr < (void *)opd->sh_addr || - ptr >= (void *)(opd->sh_addr + opd->sh_size)) + if (ptr < mas->opd_addr || ptr >= mas->opd_addr + mas->opd_size) return ptr; return dereference_function_descriptor(ptr); -- cgit v1.2.3