Set NODELETE flag after checking for NULL pointer
Commit Message
The commit b632bdd3 moved the setting of the DF_1_NODELETE flag earlier
in the dl_open_worker function. However when calling dlopen with both
RTLD_NODELETE and RTLD_NOLOAD (which in practice also requires
RTLD_LAZY), the pointer returned by _dl_map_object is NULL. This
condition is checked just after setting the flag, while it should be
done before. Fix that.
Changelog:
[BZ #19810]
* elf/dl-open.c (dl_open_worker): Set DF_1_NODELETE flag later.
---
ChangeLog | 5 +++++
elf/dl-open.c | 12 ++++++------
2 files changed, 11 insertions(+), 6 deletions(-)
Comments
On 03/11/2016 07:30 PM, Aurelien Jarno wrote:
> The commit b632bdd3 moved the setting of the DF_1_NODELETE flag earlier
> in the dl_open_worker function. However when calling dlopen with both
> RTLD_NODELETE and RTLD_NOLOAD (which in practice also requires
> RTLD_LAZY), the pointer returned by _dl_map_object is NULL. This
> condition is checked just after setting the flag, while it should be
> done before. Fix that.
How hard is it to create a test case for this?
Thanks,
Florian
On 2016-03-11 19:33, Florian Weimer wrote:
> On 03/11/2016 07:30 PM, Aurelien Jarno wrote:
> > The commit b632bdd3 moved the setting of the DF_1_NODELETE flag earlier
> > in the dl_open_worker function. However when calling dlopen with both
> > RTLD_NODELETE and RTLD_NOLOAD (which in practice also requires
> > RTLD_LAZY), the pointer returned by _dl_map_object is NULL. This
> > condition is checked just after setting the flag, while it should be
> > done before. Fix that.
>
> How hard is it to create a test case for this?
That should be relatively easy I guess. If the patch makes sense, I can
try to add one.
Aurelien
On 03/11/2016 07:43 PM, Aurelien Jarno wrote:
> On 2016-03-11 19:33, Florian Weimer wrote:
>> On 03/11/2016 07:30 PM, Aurelien Jarno wrote:
>>> The commit b632bdd3 moved the setting of the DF_1_NODELETE flag earlier
>>> in the dl_open_worker function. However when calling dlopen with both
>>> RTLD_NODELETE and RTLD_NOLOAD (which in practice also requires
>>> RTLD_LAZY), the pointer returned by _dl_map_object is NULL. This
>>> condition is checked just after setting the flag, while it should be
>>> done before. Fix that.
>>
>> How hard is it to create a test case for this?
>
> That should be relatively easy I guess. If the patch makes sense, I can
> try to add one.
The change looks reasonable and correct to me, but the dynamic linker
scares me …
Thanks,
Florian
@@ -1,3 +1,8 @@
+2016-03-09 Aurelien Jarno <aurelien@aurel32.net>
+
+ [BZ #19810]
+ * elf/dl-open.c (dl_open_worker): Set DF_1_NODELETE flag later.
+
2016-03-11 Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
* sysdeps/powerpc/powerpc32/power4/memcmp.S (memcmp): Rearrange
@@ -226,12 +226,6 @@ dl_open_worker (void *a)
args->map = new = _dl_map_object (call_map, file, lt_loaded, 0,
mode | __RTLD_CALLMAP, args->nsid);
- /* Mark the object as not deletable if the RTLD_NODELETE flags was passed.
- Do this early so that we don't skip marking the object if it was
- already loaded. */
- if (__glibc_unlikely (mode & RTLD_NODELETE))
- new->l_flags_1 |= DF_1_NODELETE;
-
/* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
set and the object is not already loaded. */
if (new == NULL)
@@ -240,6 +234,12 @@ dl_open_worker (void *a)
return;
}
+ /* Mark the object as not deletable if the RTLD_NODELETE flags was passed.
+ Do this early so that we don't skip marking the object if it was
+ already loaded. */
+ if (__glibc_unlikely (mode & RTLD_NODELETE))
+ new->l_flags_1 |= DF_1_NODELETE;
+
if (__glibc_unlikely (mode & __RTLD_SPROF))
/* This happens only if we load a DSO for 'sprof'. */
return;