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authorAndreas Schwab <schwab@redhat.com>2010-05-03 08:08:28 -0700
committerUlrich Drepper <drepper@redhat.com>2010-05-03 08:08:28 -0700
commit5a2a1d75043138e696222ced4560de2fb90b8024 (patch)
tree76c2da1388b8787ebabb9e61cf27d7510d1f5a7b /elf
parentc739ec3d81a34a87d8ae1276eab4f5880afc3476 (diff)
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Don't deadlock in __dl_iterate_phdr while (un)loading objects.
Diffstat (limited to 'elf')
-rw-r--r--elf/dl-close.c5
-rw-r--r--elf/dl-iteratephdr.c8
-rw-r--r--elf/dl-load.c3
-rw-r--r--elf/dl-object.c5
-rw-r--r--elf/dl-support.c4
-rw-r--r--elf/rtld.c1
6 files changed, 22 insertions, 4 deletions
diff --git a/elf/dl-close.c b/elf/dl-close.c
index b73a7adb1a..700e765c3c 100644
--- a/elf/dl-close.c
+++ b/elf/dl-close.c
@@ -507,6 +507,9 @@ _dl_close_worker (struct link_map *map)
size_t tls_free_end;
tls_free_start = tls_free_end = NO_TLS_OFFSET;
+ /* We modify the list of loaded objects. */
+ __rtld_lock_lock_recursive (GL(dl_load_write_lock));
+
/* Check each element of the search list to see if all references to
it are gone. */
for (unsigned int i = first_loaded; i < nloaded; ++i)
@@ -665,6 +668,8 @@ _dl_close_worker (struct link_map *map)
}
}
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
+
/* If we removed any object which uses TLS bump the generation counter. */
if (any_tls)
{
diff --git a/elf/dl-iteratephdr.c b/elf/dl-iteratephdr.c
index 44864c1b7a..5f1c20d755 100644
--- a/elf/dl-iteratephdr.c
+++ b/elf/dl-iteratephdr.c
@@ -26,7 +26,7 @@
static void
cancel_handler (void *arg __attribute__((unused)))
{
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
}
hidden_proto (__dl_iterate_phdr)
@@ -38,8 +38,8 @@ __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
struct dl_phdr_info info;
int ret = 0;
- /* Make sure we are alone. */
- __rtld_lock_lock_recursive (GL(dl_load_lock));
+ /* Make sure nobody modifies the list of loaded objects. */
+ __rtld_lock_lock_recursive (GL(dl_load_write_lock));
__libc_cleanup_push (cancel_handler, 0);
/* We have to determine the namespace of the caller since this determines
@@ -79,7 +79,7 @@ __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
/* Release the lock. */
__libc_cleanup_pop (0);
- __rtld_lock_unlock_recursive (GL(dl_load_lock));
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
return ret;
}
diff --git a/elf/dl-load.c b/elf/dl-load.c
index d8f9131dd6..0adddf5aaa 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -803,6 +803,8 @@ lose (int code, int fd, const char *name, char *realname, struct link_map *l,
(void) __close (fd);
if (l != NULL)
{
+ /* We modify the list of loaded objects. */
+ __rtld_lock_lock_recursive (GL(dl_load_write_lock));
/* Remove the stillborn object from the list and free it. */
assert (l->l_next == NULL);
if (l->l_prev == NULL)
@@ -813,6 +815,7 @@ lose (int code, int fd, const char *name, char *realname, struct link_map *l,
l->l_prev->l_next = NULL;
--GL(dl_ns)[l->l_ns]._ns_nloaded;
free (l);
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
}
free (realname);
diff --git a/elf/dl-object.c b/elf/dl-object.c
index 788e2c07b9..22a163560b 100644
--- a/elf/dl-object.c
+++ b/elf/dl-object.c
@@ -93,6 +93,9 @@ _dl_new_object (char *realname, const char *libname, int type,
new->l_scope = new->l_scope_mem;
new->l_scope_max = sizeof (new->l_scope_mem) / sizeof (new->l_scope_mem[0]);
+ /* We modify the list of loaded objects. */
+ __rtld_lock_lock_recursive (GL(dl_load_write_lock));
+
/* Counter for the scopes we have to handle. */
idx = 0;
@@ -114,6 +117,8 @@ _dl_new_object (char *realname, const char *libname, int type,
new->l_serial = GL(dl_load_adds);
++GL(dl_load_adds);
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
+
/* If we have no loader the new object acts as it. */
if (loader == NULL)
loader = new;
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 65b25750de..f94d2c4c6e 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -166,6 +166,10 @@ const ElfW(Ehdr) *_dl_sysinfo_dso;
the loaded object might as well require a call to this function.
At this time it is not anymore a problem to modify the tables. */
__rtld_lock_define_initialized_recursive (, _dl_load_lock)
+/* This lock is used to keep __dl_iterate_phdr from inspecting the
+ list of loaded objects while an object is added to or removed from
+ that list. */
+__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
#ifdef HAVE_AUX_VECTOR
diff --git a/elf/rtld.c b/elf/rtld.c
index e26b2b9e1b..90f3ff126e 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -126,6 +126,7 @@ struct rtld_global _rtld_global =
._dl_stack_flags = PF_R|PF_W|PF_X,
#ifdef _LIBC_REENTRANT
._dl_load_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
+ ._dl_load_write_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
#endif
._dl_nns = 1,
._dl_ns =