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From: "satoru at 0xcc dot net" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug libc/2683] New: dladdr() returns wrong symbol names in rare cases Date: Mon, 22 May 2006 14:57:00 -0000 [thread overview] Message-ID: <20060522145631.2683.satoru@0xcc.net> (raw) I think undefined symbols should be skipped while finding symbols from dynamic symbol tables in _dl_addr() in elf/dl-addr.c. Otherwise, it returns wrong symbol names in rare cases. Here is the code for reproducing the problem. I tested it on Debian GNU/Linux sarge on a x86_32 machine (glibc 2.3.2) but looked like the latest glibc in CVS had the same problem. % cat main.c #include <stdio.h> #define __USE_GNU 1 #include <dlfcn.h> extern void foo(); static void dummy_func() {} int main() { Dl_info info; void *p = &foo; dladdr(dummy_func, &info); if (info.dli_sname) { printf("%s\n", info.dli_sname); } return 0; } % cat foo.c void foo() { volatile int a = 0; // Make this function big. ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; ++a; } % gcc -shared -o foo.so foo.c % gcc -rdynamic main.c ./foo.so -ldl % ./a.out foo Here, "foo" shouldn't be printed. % readelf --symbols a.out | egrep 'foo|dummy_func' 13: 080484d8 505 FUNC GLOBAL DEFAULT UND foo 83: 08048594 5 FUNC LOCAL DEFAULT 12 dummy_func 104: 080484d8 505 FUNC GLOBAL DEFAULT UND foo "foo" was picked since the following condition satisfied. 0x080484d8 (foo) <= 0x08048594 (dummmy_func) < 0x80486d1 (0x080484d8 + 505) I haven't tested but I guess the following patch would solve the problem. % diff -u elf/dl-addr.c.orig elf/dl-addr.c --- elf/dl-addr.c.orig 2006-05-22 23:16:21.000000000 +0900 +++ elf/dl-addr.c 2006-05-22 23:16:42.000000000 +0900 @@ -92,6 +92,7 @@ #if defined USE_TLS && ELFW(ST_TYPE) (symtab->st_info) != STT_TLS #endif + && symtab->st_shndx != SHN_UNDEF && DL_ADDR_SYM_MATCH (match, symtab, matchsym, addr) && symtab->st_name < strtabsize) matchsym = (ElfW(Sym) *) symtab; -- Summary: dladdr() returns wrong symbol names in rare cases Product: glibc Version: unspecified Status: NEW Severity: normal Priority: P2 Component: libc AssignedTo: drepper at redhat dot com ReportedBy: satoru at 0xcc dot net CC: glibc-bugs at sources dot redhat dot com http://sourceware.org/bugzilla/show_bug.cgi?id=2683 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is.
next reply other threads:[~2006-05-22 14:57 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2006-05-22 14:57 satoru at 0xcc dot net [this message] 2006-05-24 19:25 ` [Bug libc/2683] " drepper at redhat dot com 2006-05-28 5:04 ` satoru at 0xcc dot net 2006-08-24 20:20 ` drepper at redhat dot com
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