toolchain/musl/patches/020-mips-dlsym_donot_return_address_from_undef_sym.patch

   1 >From a57cd35acf26ba6202ed6534a57f496464f431a1 Mon Sep 17 00:00:00 2001
   2 From: Szabolcs Nagy <nsz@port70.net>
   3 Date: Sat, 10 Aug 2019 23:14:40 +0000
   4 Subject: [PATCH] make relocation time symbol lookup and dlsym consistent
   5
   6 Using common code path for all symbol lookups fixes three dlsym issues:
   7
   8 - st_shndx of STT_TLS symbols were not checked and thus an undefined
   9   tls symbol reference could be incorrectly treated as a definition
  10   (the sysv hash lookup returns undefined symbols, gnu does not, so should
  11   be rare in practice).
  12
  13 - symbol binding was not checked so a hidden symbol may be returned
  14   (in principle STB_LOCAL symbols may appear in the dynamic symbol table
  15   for hidden symbols, but linkers most likely don't produce it).
  16
  17 - mips specific behaviour was not applied (ARCH_SYM_REJECT_UND) so
  18   undefined symbols may be returned on mips.
  19
  20 always_inline is used to avoid relocation performance regression, the
  21 code generation for find_sym should not be affected.
  22 ---
  23  ldso/dynlink.c | 84 +++++++++++++++++++-------------------------------
  24  1 file changed, 31 insertions(+), 53 deletions(-)
  25
  26 --- a/ldso/dynlink.c
  27 +++ b/ldso/dynlink.c
  28 @@ -283,12 +283,16 @@ static Sym *gnu_lookup_filtered(uint32_t
  29  #define ARCH_SYM_REJECT_UND(s) 0
  30  #endif
  31
  32 -static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
  33 +#if defined(__GNUC__)
  34 +__attribute__((always_inline))
  35 +#endif
  36 +static inline struct symdef find_sym2(struct dso *dso, const char *s, int need_def, int use_deps)
  37  {
  38         uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
  39         size_t ghm = 1ul << gh % (8*sizeof(size_t));
  40         struct symdef def = {0};
  41 -       for (; dso; dso=dso->syms_next) {
  42 +       struct dso **deps = use_deps ? dso->deps : 0;
  43 +       for (; dso; dso=use_deps ? *deps++ : dso->syms_next) {
  44                 Sym *sym;
  45                 if ((ght = dso->ghashtab)) {
  46                         sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
  47 @@ -313,6 +317,11 @@ static struct symdef find_sym(struct dso
  48         return def;
  49  }
  50
  51 +static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
  52 +{
  53 +       return find_sym2(dso, s, need_def, 0);
  54 +}
  55 +
  56  static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
  57  {
  58         unsigned char *base = dso->base;
  59 @@ -2118,58 +2127,27 @@ static void *addr2dso(size_t a)
  60
  61  static void *do_dlsym(struct dso *p, const char *s, void *ra)
  62  {
  63 -       size_t i;
  64 -       uint32_t h = 0, gh = 0, *ght;
  65 -       Sym *sym;
  66 -       if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
  67 -               if (p == RTLD_DEFAULT) {
  68 -                       p = head;
  69 -               } else if (p == RTLD_NEXT) {
  70 -                       p = addr2dso((size_t)ra);
  71 -                       if (!p) p=head;
  72 -                       p = p->next;
  73 -               }
  74 -               struct symdef def = find_sym(p, s, 0);
  75 -               if (!def.sym) goto failed;
  76 -               if ((def.sym->st_info&0xf) == STT_TLS)
  77 -                       return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
  78 -               if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
  79 -                       return def.dso->funcdescs + (def.sym - def.dso->syms);
  80 -               return laddr(def.dso, def.sym->st_value);
  81 -       }
  82 -       if (__dl_invalid_handle(p))
  83 +       int use_deps = 0;
  84 +       if (p == head || p == RTLD_DEFAULT) {
  85 +               p = head;
  86 +       } else if (p == RTLD_NEXT) {
  87 +               p = addr2dso((size_t)ra);
  88 +               if (!p) p=head;
  89 +               p = p->next;
  90 +       } else if (__dl_invalid_handle(p)) {
  91 +               return 0;
  92 +       } else
  93 +               use_deps = 1;
  94 +       struct symdef def = find_sym2(p, s, 0, use_deps);
  95 +       if (!def.sym) {
  96 +               error("Symbol not found: %s", s);
  97                 return 0;
  98 -       if ((ght = p->ghashtab)) {
  99 -               gh = gnu_hash(s);
 100 -               sym = gnu_lookup(gh, ght, p, s);
 101 -       } else {
 102 -               h = sysv_hash(s);
 103 -               sym = sysv_lookup(s, h, p);
 104 -       }
 105 -       if (sym && (sym->st_info&0xf) == STT_TLS)
 106 -               return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value-DTP_OFFSET});
 107 -       if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
 108 -               return p->funcdescs + (sym - p->syms);
 109 -       if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
 110 -               return laddr(p, sym->st_value);
 111 -       for (i=0; p->deps[i]; i++) {
 112 -               if ((ght = p->deps[i]->ghashtab)) {
 113 -                       if (!gh) gh = gnu_hash(s);
 114 -                       sym = gnu_lookup(gh, ght, p->deps[i], s);
 115 -               } else {
 116 -                       if (!h) h = sysv_hash(s);
 117 -                       sym = sysv_lookup(s, h, p->deps[i]);
 118 -               }
 119 -               if (sym && (sym->st_info&0xf) == STT_TLS)
 120 -                       return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value-DTP_OFFSET});
 121 -               if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
 122 -                       return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
 123 -               if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
 124 -                       return laddr(p->deps[i], sym->st_value);
 125         }
 126 -failed:
 127 -       error("Symbol not found: %s", s);
 128 -       return 0;
 129 +       if ((def.sym->st_info&0xf) == STT_TLS)
 130 +               return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
 131 +       if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
 132 +               return def.dso->funcdescs + (def.sym - def.dso->syms);
 133 +       return laddr(def.dso, def.sym->st_value);
 134  }
 135
 136  int dladdr(const void *addr_arg, Dl_info *info)