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[Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
- From: "ian at airs dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: 7 Oct 2006 01:52:35 -0000
- Subject: [Bug linuxthreads/3318] New: Overriding free which clobbers data and calls pthread_getspecific can get bad value (linuxthreads)
- Reply-to: sourceware-bugzilla at sourceware dot org
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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