[git commit] libdl: fix local symbol's address handling in dladdr

Carmelo Amoroso carmelo.amoroso at st.com
Tue May 10 09:53:41 UTC 2011


commit: http://git.uclibc.org/uClibc/commit/?id=974d3140577ac740c8db2f1ad9635c4ba591361e
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/master

Fix dladdr to correctly handle local function's address so backtrace_symbols
print only the function address for these function, instead of showing the name
of nearest one.
Indeed the dladdr walk through the hash table to find the nearest symbol, that
doesn't contain local symbols.

Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono at st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso at st.com>
---
 ldso/include/dl-defs.h |    8 ++++++++
 ldso/libdl/libdl.c     |   12 ++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/ldso/include/dl-defs.h b/ldso/include/dl-defs.h
index be0a81d..88ff815 100644
--- a/ldso/include/dl-defs.h
+++ b/ldso/include/dl-defs.h
@@ -179,6 +179,14 @@ typedef struct {
 #define DL_LOOKUP_ADDRESS(ADDRESS) (ADDRESS)
 #endif
 
+/* On some architectures dladdr can't use st_size of all symbols this way.  */
+#define DL_ADDR_SYM_MATCH(SYM_ADDR, SYM, MATCHSYM, ADDR)				\
+  ((ADDR) >= (SYM_ADDR)													\
+   && ((((SYM)->st_shndx == SHN_UNDEF || (SYM)->st_size == 0)			\
+        && (ADDR) == (SYM_ADDR))										\
+       || (ADDR) < (SYM_ADDR) + (SYM)->st_size)							\
+   && (!(MATCHSYM) || MATCHSYM < (SYM_ADDR)))
+
 /* Use this macro to convert a pointer to a function's entry point to
  * a pointer to function.  The pointer is assumed to have already been
  * relocated.  LOADADDR is passed because it may contain additional
diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c
index 68cd579..b80495e 100644
--- a/ldso/libdl/libdl.c
+++ b/ldso/libdl/libdl.c
@@ -1067,7 +1067,11 @@ int dladdr(const void *__address, Dl_info * __info)
 					ElfW(Addr) symbol_addr;
 
 					symbol_addr = (ElfW(Addr)) DL_RELOC_ADDR(pelf->loadaddr, symtab[si].st_value);
-					if (symbol_addr <= (ElfW(Addr))__address && (!sf || sa < symbol_addr)) {
+					if ((symtab[si].st_shndx != SHN_UNDEF
+						 || symtab[si].st_value != 0)
+						&& ELF_ST_TYPE(symtab[si].st_info) != STT_TLS
+						&& DL_ADDR_SYM_MATCH(symbol_addr, &symtab[si], sa,
+											 (ElfW(Addr)) __address)) {
 						sa = symbol_addr;
 						sn = si;
 						sf = 1;
@@ -1083,7 +1087,11 @@ int dladdr(const void *__address, Dl_info * __info)
 				ElfW(Addr) symbol_addr;
 
 				symbol_addr = (ElfW(Addr)) DL_RELOC_ADDR(pelf->loadaddr, symtab[si].st_value);
-				if (symbol_addr <= (ElfW(Addr))__address && (!sf || sa < symbol_addr)) {
+				if ((symtab[si].st_shndx != SHN_UNDEF
+					 || symtab[si].st_value != 0)
+					&& ELF_ST_TYPE(symtab[si].st_info) != STT_TLS
+					&& DL_ADDR_SYM_MATCH(symbol_addr, &symtab[si], sa,
+										 (ElfW(Addr)) __address)) {
 					sa = symbol_addr;
 					sn = si;
 					sf = 1;
-- 
1.7.3.4



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