--- /dev/null
+>From a57cd35acf26ba6202ed6534a57f496464f431a1 Mon Sep 17 00:00:00 2001
+From: Szabolcs Nagy <nsz@port70.net>
+Date: Sat, 10 Aug 2019 23:14:40 +0000
+Subject: [PATCH] make relocation time symbol lookup and dlsym consistent
+
+Using common code path for all symbol lookups fixes three dlsym issues:
+
+- st_shndx of STT_TLS symbols were not checked and thus an undefined
+ tls symbol reference could be incorrectly treated as a definition
+ (the sysv hash lookup returns undefined symbols, gnu does not, so should
+ be rare in practice).
+
+- symbol binding was not checked so a hidden symbol may be returned
+ (in principle STB_LOCAL symbols may appear in the dynamic symbol table
+ for hidden symbols, but linkers most likely don't produce it).
+
+- mips specific behaviour was not applied (ARCH_SYM_REJECT_UND) so
+ undefined symbols may be returned on mips.
+
+always_inline is used to avoid relocation performance regression, the
+code generation for find_sym should not be affected.
+---
+ ldso/dynlink.c | 84 +++++++++++++++++++-------------------------------
+ 1 file changed, 31 insertions(+), 53 deletions(-)
+
+--- a/ldso/dynlink.c
++++ b/ldso/dynlink.c
+@@ -283,12 +283,16 @@ static Sym *gnu_lookup_filtered(uint32_t
+ #define ARCH_SYM_REJECT_UND(s) 0
+ #endif
+
+-static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
++#if defined(__GNUC__)
++__attribute__((always_inline))
++#endif
++static inline struct symdef find_sym2(struct dso *dso, const char *s, int need_def, int use_deps)
+ {
+ uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
+ size_t ghm = 1ul << gh % (8*sizeof(size_t));
+ struct symdef def = {0};
+- for (; dso; dso=dso->syms_next) {
++ struct dso **deps = use_deps ? dso->deps : 0;
++ for (; dso; dso=use_deps ? *deps++ : dso->syms_next) {
+ Sym *sym;
+ if ((ght = dso->ghashtab)) {
+ sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
+@@ -313,6 +317,11 @@ static struct symdef find_sym(struct dso
+ return def;
+ }
+
++static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
++{
++ return find_sym2(dso, s, need_def, 0);
++}
++
+ static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
+ {
+ unsigned char *base = dso->base;
+@@ -2118,58 +2127,27 @@ static void *addr2dso(size_t a)
+
+ static void *do_dlsym(struct dso *p, const char *s, void *ra)
+ {
+- size_t i;
+- uint32_t h = 0, gh = 0, *ght;
+- Sym *sym;
+- if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
+- if (p == RTLD_DEFAULT) {
+- p = head;
+- } else if (p == RTLD_NEXT) {
+- p = addr2dso((size_t)ra);
+- if (!p) p=head;
+- p = p->next;
+- }
+- struct symdef def = find_sym(p, s, 0);
+- if (!def.sym) goto failed;
+- if ((def.sym->st_info&0xf) == STT_TLS)
+- return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
+- if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
+- return def.dso->funcdescs + (def.sym - def.dso->syms);
+- return laddr(def.dso, def.sym->st_value);
+- }
+- if (__dl_invalid_handle(p))
++ int use_deps = 0;
++ if (p == head || p == RTLD_DEFAULT) {
++ p = head;
++ } else if (p == RTLD_NEXT) {
++ p = addr2dso((size_t)ra);
++ if (!p) p=head;
++ p = p->next;
++ } else if (__dl_invalid_handle(p)) {
++ return 0;
++ } else
++ use_deps = 1;
++ struct symdef def = find_sym2(p, s, 0, use_deps);
++ if (!def.sym) {
++ error("Symbol not found: %s", s);
+ return 0;
+- if ((ght = p->ghashtab)) {
+- gh = gnu_hash(s);
+- sym = gnu_lookup(gh, ght, p, s);
+- } else {
+- h = sysv_hash(s);
+- sym = sysv_lookup(s, h, p);
+- }
+- if (sym && (sym->st_info&0xf) == STT_TLS)
+- return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
+- if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
+- return p->funcdescs + (sym - p->syms);
+- if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
+- return laddr(p, sym->st_value);
+- for (i=0; p->deps[i]; i++) {
+- if ((ght = p->deps[i]->ghashtab)) {
+- if (!gh) gh = gnu_hash(s);
+- sym = gnu_lookup(gh, ght, p->deps[i], s);
+- } else {
+- if (!h) h = sysv_hash(s);
+- sym = sysv_lookup(s, h, p->deps[i]);
+- }
+- if (sym && (sym->st_info&0xf) == STT_TLS)
+- return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
+- if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
+- return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
+- if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
+- return laddr(p->deps[i], sym->st_value);
+ }
+-failed:
+- error("Symbol not found: %s", s);
+- return 0;
++ if ((def.sym->st_info&0xf) == STT_TLS)
++ return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
++ if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
++ return def.dso->funcdescs + (def.sym - def.dso->syms);
++ return laddr(def.dso, def.sym->st_value);
+ }
+
+ int dladdr(const void *addr_arg, Dl_info *info)
projects / openwrt / staging / chunkeey.git / blobdiff