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* [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
@ 2006-10-07 1:52 ian at airs dot com
2006-10-07 1:56 ` [Bug linuxthreads/3318] " ian at airs dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: ian at airs dot com @ 2006-10-07 1:52 UTC (permalink / raw)
To: glibc-bugs
This is the linuxthreads version of bugzilla PR 3317, which I reported for NPTL.
If I override the libc free() function, and change that function to clobber some
bytes of the data, and then call pthread_getspecific from that function,
pthread_getspecific can return bad data. This is because
__pthread_destroy_specifics frees memory before clearing the pointer to it.
This happens around line 200:
if (THREAD_GETMEM_NC(self, p_specific[i]) != NULL) {
free(THREAD_GETMEM_NC(self, p_specific[i]));
THREAD_SETMEM_NC(self, p_specific[i], NULL);
}
This should be rewritten to call THREAD_GETMEM_NC, then THREAD_SETMEM_NC, then free.
I will attach a test case which shows the problem on i686-pc-linux-gnu using
Fedora Core 4 with glibc-2.3.6-3 when setting the environment variable
LD_ASSUME_KERNEL to 2.4.19.
--
Summary: Overriding free which clobbers data and calls
pthread_getspecific can get bad value (linuxthreads)
Product: glibc
Version: 2.3.6
Status: NEW
Severity: normal
Priority: P2
Component: linuxthreads
AssignedTo: drow at false dot org
ReportedBy: ian at airs dot com
CC: glibc-bugs at sources dot redhat dot com
http://sourceware.org/bugzilla/show_bug.cgi?id=3318
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* [Bug linuxthreads/3318] Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
2006-10-07 1:52 [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads) ian at airs dot com
@ 2006-10-07 1:56 ` ian at airs dot com
2006-10-31 15:31 ` drow at sources dot redhat dot com
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: ian at airs dot com @ 2006-10-07 1:56 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From ian at airs dot com 2006-10-07 01:56 -------
Created an attachment (id=1357)
--> (http://sourceware.org/bugzilla/attachment.cgi?id=1357&action=view)
Test case
This test case crashes for me on i686-pc-linux-gnu running Fedora Core 4 with
glibc-2.3.6-3 when I set the environment variable LD_ASSUME_KERNEL to 2.4.19.
In the __libc_free routine, pthread_getspecific returns garbage.
This isn't the simplest possible test case--it's a modification of the NPTL
test case. The call to abort winds up hanging as the pthread code waits for a
lock, so I put in an alarm to get the program to actually exit. The hang is
probably due to the bug I reported in bugzilla PR 2948, which has been fixed in
the mainline sources.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=3318
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* [Bug linuxthreads/3318] Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
2006-10-07 1:52 [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads) ian at airs dot com
2006-10-07 1:56 ` [Bug linuxthreads/3318] " ian at airs dot com
@ 2006-10-31 15:31 ` drow at sources dot redhat dot com
2006-10-31 21:49 ` drow at sources dot redhat dot com
2006-10-31 21:50 ` drow at sources dot redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: drow at sources dot redhat dot com @ 2006-10-31 15:31 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drow at sources dot redhat dot com 2006-10-31 15:31 -------
Sorry, but I don't think there's any point in diverging from NPTL on this point;
LinuxThreads is strictly end of life now. It's reasonably easy to work around
this bug and in fact I'm not sure how you ever encountered it; the sequence
number is first, and if you clobber that, pthread_getspecific will return NULL.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
http://sourceware.org/bugzilla/show_bug.cgi?id=3318
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* [Bug linuxthreads/3318] Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
2006-10-07 1:52 [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads) ian at airs dot com
2006-10-07 1:56 ` [Bug linuxthreads/3318] " ian at airs dot com
2006-10-31 15:31 ` drow at sources dot redhat dot com
@ 2006-10-31 21:49 ` drow at sources dot redhat dot com
2006-10-31 21:50 ` drow at sources dot redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: drow at sources dot redhat dot com @ 2006-10-31 21:49 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drow at sources dot redhat dot com 2006-10-31 21:49 -------
After talking to Ian...
--
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|WONTFIX |
http://sourceware.org/bugzilla/show_bug.cgi?id=3318
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* [Bug linuxthreads/3318] Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
2006-10-07 1:52 [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads) ian at airs dot com
` (2 preceding siblings ...)
2006-10-31 21:49 ` drow at sources dot redhat dot com
@ 2006-10-31 21:50 ` drow at sources dot redhat dot com
3 siblings, 0 replies; 5+ messages in thread
From: drow at sources dot redhat dot com @ 2006-10-31 21:50 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drow at sources dot redhat dot com 2006-10-31 21:50 -------
... I checked in a fix for this, in case LinuxThreads ever builds again.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution| |FIXED
http://sourceware.org/bugzilla/show_bug.cgi?id=3318
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2006-10-07 1:52 [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads) ian at airs dot com
2006-10-07 1:56 ` [Bug linuxthreads/3318] " ian at airs dot com
2006-10-31 15:31 ` drow at sources dot redhat dot com
2006-10-31 21:49 ` drow at sources dot redhat dot com
2006-10-31 21:50 ` drow at sources dot redhat dot com
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