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authorSzabolcs Nagy <nsz@port70.net>2019-08-10 23:14:40 +0000
committerRich Felker <dalias@aerifal.cx>2019-08-12 18:25:38 -0400
commitf2435263d7366a81b734c8a69877f1359083ce8c (patch)
tree17c4cc1efc3840ccbe89196dc94702a92d37b18d /ldso/dynlink.c
parent1f060ed2fb0b35f85118a425f5eed3299fef58d3 (diff)
downloadmusl-f2435263d7366a81b734c8a69877f1359083ce8c.tar.gz
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.
Diffstat (limited to 'ldso/dynlink.c')
-rw-r--r--ldso/dynlink.c84
1 files changed, 31 insertions, 53 deletions
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index b9b2e96c..a124e704 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -283,12 +283,16 @@ static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso,
#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 *dso, const char *s, int need_def)
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;
@@ -2123,58 +2132,27 @@ 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;
- 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;
+ } 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 ((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)