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Add forced deletion support to _dl_close_worker 

https://sourceware.org/bugzilla/show_bug.cgi?id=17833

I've a shared library that contains both undefined and unique symbols.
Then I try to call the following sequence of dlopen:

1. dlopen("./libfoo.so", RTLD_NOW)
2. dlopen("./libfoo.so", RTLD_LAZY | RTLD_GLOBAL)

First dlopen call terminates with error because of undefined symbols,
but STB_GNU_UNIQUE ones set DF_1_NODELETE flag and hence block library
in the memory.

The library goes into inconsistent state as several structures remain
uninitialized. For instance, relocations for GOT table were not performed.

By the time of second dlopen call this library looks like as it would be
fully initialized but this is not true: any call through incorrect GOT
table leads to segmentation fault.  On some systems this inconsistency
triggers assertions in the dynamic linker.

This patch adds a parameter to _dl_close_worker to implement forced object
deletion in case of dlopen() failure:

1. Clears DF_1_NODELETE bit if forced, to allow library to be removed from
memory.
2. For each unique symbol that is defined in this object clears
appropriate entry in _ns_unique_sym_table.

	[BZ #17833]
	* elf/Makefile (tests): Add tst-nodelete.
	(modules-names): Add tst-nodelete-uniquemod.
	(tst-nodelete-uniquemod.so-no-z-defs): New.
	(tst-nodelete-rtldmod.so-no-z-defs): Likewise.
	(tst-nodelete-zmod.so-no-z-defs): Likewise.
	($(objpfx)tst-nodelete): Likewise.
	($(objpfx)tst-nodelete.out): Likewise.
	(LDFLAGS-tst-nodelete): Likewise.
	(LDFLAGS-tst-nodelete-zmod.so): Likewise.
	* elf/dl-close.c (_dl_close_worker): Add a parameter to
	implement forced object deletion.
	(_dl_close): Pass false to _dl_close_worker.
	* elf/dl-open.c (_dl_open): Pass true to _dl_close_worker.
	* elf/tst-nodelete.cc: New file.
	* elf/tst-nodeletelib.cc: Likewise.
	* elf/tst-znodeletelib.cc: Likewise.
	* include/dlfcn.h (_dl_close_worker): Add a new parameter.
This commit is contained in:
Pavel Kopyl 2015-07-07 18:45:46 +03:00 committed by H.J. Lu
parent 890b7a4b33
commit 02d5e5d94a
11 changed files with 167 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
ChangeLog
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@ -1,3 +1,25 @@
2015-07-07 Pavel Kopyl <p.kopyl@samsung.com>
Mikhail Ilin <m.ilin@samsung.com>
[BZ #17833]
* elf/Makefile (tests): Add tst-nodelete.
(modules-names): Add tst-nodelete-uniquemod.
(tst-nodelete-uniquemod.so-no-z-defs): New.
(tst-nodelete-rtldmod.so-no-z-defs): Likewise.
(tst-nodelete-zmod.so-no-z-defs): Likewise.
($(objpfx)tst-nodelete): Likewise.
($(objpfx)tst-nodelete.out): Likewise.
(LDFLAGS-tst-nodelete): Likewise.
(LDFLAGS-tst-nodelete-zmod.so): Likewise.
* elf/dl-close.c (_dl_close_worker): Add a parameter to
implement forced object deletion.
(_dl_close): Pass false to _dl_close_worker.
* elf/dl-open.c (_dl_open): Pass true to _dl_close_worker.
* elf/tst-nodelete.cc: New file.
* elf/tst-nodeletelib.cc: Likewise.
* elf/tst-znodeletelib.cc: Likewise.
* include/dlfcn.h (_dl_close_worker): Add a new parameter.
2015-07-07 Stefan Liebler <stli@linux.vnet.ibm.com>
[BZ #18508]

26
NEWS
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@ -14,19 +14,19 @@ Version 2.22
16526, 16538, 16559, 16560, 16704, 16783, 16850, 17053, 17090, 17195,
17269, 17293, 17322, 17403, 17523, 17542, 17569, 17581, 17588, 17596,
17620, 17621, 17628, 17631, 17692, 17711, 17715, 17776, 17779, 17792,
17836, 17841, 17912, 17916, 17930, 17932, 17944, 17949, 17964, 17965,
17967, 17969, 17977, 17978, 17987, 17991, 17996, 17998, 17999, 18007,
18019, 18020, 18029, 18030, 18032, 18034, 18036, 18038, 18039, 18042,
18043, 18046, 18047, 18049, 18068, 18080, 18093, 18100, 18104, 18110,
18111, 18116, 18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210,
18211, 18217, 18219, 18220, 18221, 18234, 18244, 18245, 18247, 18287,
18319, 18324, 18333, 18346, 18371, 18397, 18409, 18410, 18412, 18418,
18422, 18434, 18435, 18444, 18468, 18469, 18470, 18479, 18483, 18495,
18496, 18497, 18498, 18502, 18507, 18508, 18512, 18513, 18519, 18520,
18522, 18527, 18528, 18529, 18530, 18532, 18533, 18534, 18536, 18539,
18540, 18542, 18544, 18545, 18546, 18547, 18549, 18553, 18558, 18569,
18583, 18585, 18586, 18592, 18593, 18594, 18602, 18612, 18613, 18619,
18633.
17833, 17836, 17841, 17912, 17916, 17930, 17932, 17944, 17949, 17964,
17965, 17967, 17969, 17977, 17978, 17987, 17991, 17996, 17998, 17999,
18007, 18019, 18020, 18029, 18030, 18032, 18034, 18036, 18038, 18039,
18042, 18043, 18046, 18047, 18049, 18068, 18080, 18093, 18100, 18104,
18110, 18111, 18116, 18125, 18128, 18138, 18185, 18196, 18197, 18206,
18210, 18211, 18217, 18219, 18220, 18221, 18234, 18244, 18245, 18247,
18287, 18319, 18324, 18333, 18346, 18371, 18397, 18409, 18410, 18412,
18418, 18422, 18434, 18435, 18444, 18468, 18469, 18470, 18479, 18483,
18495, 18496, 18497, 18498, 18502, 18507, 18508, 18512, 18513, 18519,
18520, 18522, 18527, 18528, 18529, 18530, 18532, 18533, 18534, 18536,
18539, 18540, 18542, 18544, 18545, 18546, 18547, 18549, 18553, 18558,
18569, 18583, 18585, 18586, 18592, 18593, 18594, 18602, 18612, 18613,
18619, 18633.
* Cache information can be queried via sysconf() function on s390 e.g. with
_SC_LEVEL1_ICACHE_SIZE as argument.

17
elf/Makefile
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@ -132,7 +132,7 @@ tests += $(tests-static)
ifeq (yes,$(build-shared))
tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
constload1 order noload filter unload \
reldep reldep2 reldep3 reldep4 nodelete nodelete2 \
reldep reldep2 reldep3 reldep4 nodelete nodelete2 tst-nodelete \
nodlopen nodlopen2 neededtest neededtest2 \
neededtest3 neededtest4 unload2 lateglobal initfirst global \
restest2 next dblload dblunload reldep5 reldep6 reldep7 reldep8 \
@ -207,7 +207,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
tst-unique1mod1 tst-unique1mod2 \
tst-unique2mod1 tst-unique2mod2 \
tst-auditmod9a tst-auditmod9b \
$(if $(CXX),tst-unique3lib tst-unique3lib2 tst-unique4lib) \
$(if $(CXX),tst-unique3lib tst-unique3lib2 tst-unique4lib \
tst-nodelete-uniquemod) \
tst-nodelete-rtldmod tst-nodelete-zmod \
tst-initordera1 tst-initorderb1 \
tst-initordera2 tst-initorderb2 \
tst-initordera3 tst-initordera4 \
@ -591,6 +593,9 @@ ifuncmod5.so-no-z-defs = yes
ifuncmod6.so-no-z-defs = yes
tst-auditmod9a.so-no-z-defs = yes
tst-auditmod9b.so-no-z-defs = yes
tst-nodelete-uniquemod.so-no-z-defs = yes
tst-nodelete-rtldmod.so-no-z-defs = yes
tst-nodelete-zmod.so-no-z-defs = yes
ifeq ($(build-shared),yes)
# Build all the modules even when not actually running test programs.
@ -1153,6 +1158,14 @@ $(objpfx)tst-unique3.out: $(objpfx)tst-unique3lib2.so
$(objpfx)tst-unique4: $(objpfx)tst-unique4lib.so
$(objpfx)tst-nodelete: $(libdl)
$(objpfx)tst-nodelete.out: $(objpfx)tst-nodelete-uniquemod.so \
$(objpfx)tst-nodelete-rtldmod.so \
$(objpfx)tst-nodelete-zmod.so
LDFLAGS-tst-nodelete = -rdynamic
LDFLAGS-tst-nodelete-zmod.so = -Wl,--enable-new-dtags,-z,nodelete
$(objpfx)tst-initorder-cmp.out: tst-initorder.exp $(objpfx)tst-initorder.out
cmp $^ > $@; \
$(evaluate-test)

33
elf/dl-close.c
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@ -108,7 +108,7 @@ remove_slotinfo (size_t idx, struct dtv_slotinfo_list *listp, size_t disp,
void
_dl_close_worker (struct link_map *map)
_dl_close_worker (struct link_map *map, bool force)
{
/* One less direct use. */
--map->l_direct_opencount;
@ -152,6 +152,10 @@ _dl_close_worker (struct link_map *map)
l->l_idx = idx;
maps[idx] = l;
++idx;
/* Clear DF_1_NODELETE to force object deletion. */
if (force)
l->l_flags_1 &= ~DF_1_NODELETE;
}
assert (idx == nloaded);
@ -635,6 +639,31 @@ _dl_close_worker (struct link_map *map)
}
}
/* Reset unique symbols if forced. */
if (force)
{
struct unique_sym_table *tab = &ns->_ns_unique_sym_table;
__rtld_lock_lock_recursive (tab->lock);
struct unique_sym *entries = tab->entries;
if (entries != NULL)
{
size_t idx, size = tab->size;
for (idx = 0; idx < size; ++idx)
{
/* Clear unique symbol entries that belong to this
object. */
if (entries[idx].name != NULL
&& entries[idx].map == imap)
{
entries[idx].name = NULL;
entries[idx].hashval = 0;
tab->n_elements--;
}
}
}
__rtld_lock_unlock_recursive (tab->lock);
}
/* We can unmap all the maps at once. We determined the
start address and length when we loaded the object and
the `munmap' call does the rest. */
@ -782,7 +811,7 @@ _dl_close (void *_map)
/* Acquire the lock. */
__rtld_lock_lock_recursive (GL(dl_load_lock));
_dl_close_worker (map);
_dl_close_worker (map, false);
__rtld_lock_unlock_recursive (GL(dl_load_lock));
}

2
elf/dl-open.c
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@ -670,7 +670,7 @@ no more namespaces available for dlmopen()"));
if ((mode & __RTLD_AUDIT) == 0)
GL(dl_tls_dtv_gaps) = true;
_dl_close_worker (args.map);
_dl_close_worker (args.map, true);
}
assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);

6
elf/tst-nodelete-rtldmod.cc Normal file
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@ -0,0 +1,6 @@
extern int not_exist (void);
int foo (void)
{
return not_exist ();
}

14
elf/tst-nodelete-uniquemod.cc Normal file
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@ -0,0 +1,14 @@
extern int not_exist (void);
inline int make_unique (void)
{
/* Static variables in inline functions and classes
generate STB_GNU_UNIQUE symbols. */
static int unique;
return ++unique;
}
int foo (void)
{
return make_unique () + not_exist ();
}

6
elf/tst-nodelete-zmod.cc Normal file
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@ -0,0 +1,6 @@
extern int not_exist (void);
int foo (void)
{
return not_exist ();
}

51
elf/tst-nodelete.cc Normal file
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@ -0,0 +1,51 @@
#include "../dlfcn/dlfcn.h"
#include <stdio.h>
#include <stdlib.h>
static int
do_test (void)
{
int result = 0;
/* This is a test for correct handling of dlopen failures for library that
is loaded with RTLD_NODELETE flag. The first dlopen should fail because
of undefined symbols in shared library. The second dlopen then verifies
that library was properly unloaded. */
if (dlopen ("tst-nodelete-rtldmod.so", RTLD_NOW | RTLD_NODELETE) != NULL
|| dlopen ("tst-nodelete-rtldmod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
{
printf ("RTLD_NODELETE test failed\n");
result = 1;
}
/* This is a test for correct handling of dlopen failures for library that
is linked with '-z nodelete' option and hence has DF_1_NODELETE flag.
The first dlopen should fail because of undefined symbols in shared
library. The second dlopen then verifies that library was properly
unloaded. */
if (dlopen ("tst-nodelete-zmod.so", RTLD_NOW) != NULL
|| dlopen ("tst-nodelete-zmod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
{
printf ("-z nodelete test failed\n");
result = 1;
}
/* This is a test for correct handling of dlopen failures for library
with unique symbols. The first dlopen should fail because of undefined
symbols in shared library. The second dlopen then verifies that library
was properly unloaded. */
if (dlopen ("tst-nodelete-uniquemod.so", RTLD_NOW) != NULL
|| dlopen ("tst-nodelete-uniquemod.so", RTLD_LAZY | RTLD_NOLOAD) != NULL)
{
printf ("Unique symbols test failed\n");
result = 1;
}
if (result == 0)
printf ("SUCCESS\n");
return result;
}
#define TEST_FUNCTION do_test ()
#include "../test-skeleton.c"

6
elf/tst-znodelete-zlib.cc Normal file
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@ -0,0 +1,6 @@
extern int not_exist (void);
int foo (void)
{
return not_exist ();
}

3
include/dlfcn.h
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@ -54,7 +54,8 @@ struct link_map;
extern void _dl_close (void *map) attribute_hidden;
/* Same as above, but without locking and safety checks for user
provided map arguments. */
extern void _dl_close_worker (struct link_map *map) attribute_hidden;
extern void _dl_close_worker (struct link_map *map, bool force)
attribute_hidden;
/* Look up NAME in shared object HANDLE (which may be RTLD_DEFAULT or
RTLD_NEXT). WHO is the calling function, for RTLD_NEXT. Returns