[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [livepatch-build-tools part3 2/3] create-diff-object: Extend patchability verification: STN_UNDEF
During verification check if all sections do not contain any entries with undefined symbols (STN_UNDEF). This situation can happen when a section is copied over from its original object to a patched object, but various symbols related to the section are not copied along. This scenario happens typically during stacked hotpatches creation (between 2 different hotpatch modules). Signed-off-by: Pawel Wieczorkiewicz <wipawel@xxxxxxxxx> Reviewed-by: Martin Pohlack <mpohlack@xxxxxxxxx> Reviewed-by: Bjoern Doebel <doebel@xxxxxxxxx> Reviewed-by: Norbert Manthey <nmanthey@xxxxxxxxx> Reviewed-by: Andra-Irina Paraschiv <andraprs@xxxxxxxxxx> CR: https://code.amazon.com/reviews/CR-7368645 --- create-diff-object.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 60 insertions(+) diff --git a/create-diff-object.c b/create-diff-object.c index af2245c..96b6716 100644 --- a/create-diff-object.c +++ b/create-diff-object.c @@ -1448,6 +1448,31 @@ static void kpatch_print_changes(struct kpatch_elf *kelf) } } +static inline int get_section_entry_size(const struct section *sec, struct kpatch_elf *kelf) +{ + int entry_size; + + /* + * Base sections typically do not define fixed size elements. + * Detect section's element size in case it's a special section. + * Otherwise, skip it due to an unknown sh_entsize. + */ + entry_size = sec->sh.sh_entsize; + if (entry_size == 0) { + struct special_section *special; + + /* Find special section group_size. */ + for (special = special_sections; special->name; special++) { + /* Match sections starting with special->name prefix */ + if (!strncmp(sec->name, special->name, strlen(special->name))) { + return special->group_size(kelf, 0); + } + } + } + + return entry_size; +} + static void kpatch_verify_patchability(struct kpatch_elf *kelf) { struct section *sec; @@ -1471,6 +1496,41 @@ static void kpatch_verify_patchability(struct kpatch_elf *kelf) errs++; } + if (sec->include) { + if (!is_standard_section(sec) && !is_rela_section(sec) && + !is_debug_section(sec) && !is_special_section(sec)) { + if (!is_referenced_section(sec, kelf)) { + log_normal("section %s included, but not referenced\n", sec->name); + errs++; + } + } + + /* Check if a RELA section does not contain any entries with + * undefined symbols (STN_UNDEF). This situation can happen + * when a section is copied over from its original object to + * a patched object, but various symbols related to the section + * are not copied along. + */ + if (is_rela_section(sec)) { + int offset, entry_size = get_section_entry_size(sec, kelf); + struct rela *rela; + + for ( offset = 0; offset < sec->base->data->d_size && entry_size; offset += entry_size ) { + list_for_each_entry(rela, &sec->relas, list) { + if (rela->offset < offset || rela->offset >= offset + entry_size) + continue; + + if ((GELF_R_SYM(rela->rela.r_info) == STN_UNDEF) || + (!rela->sym->include && (rela->sym->status == SAME))) { + log_normal("section %s has an entry with a STN_UNDEF symbol: %s\n", + sec->name, rela->sym->name ? rela->sym->name : "none"); + errs++; + } + } + } + } + } + /* * ensure we aren't including .data.* or .bss.* * (.data.unlikely is ok b/c it only has __warned vars) -- 2.16.5 Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich Ust-ID: DE 289 237 879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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