diff options
| author | Jim Keniston <jkenisto@us.ibm.com> | 2005-11-23 13:37:42 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-23 16:08:39 -0800 |
| commit | 8bf1101bd52573e0573e374d56d2feecdbb5e444 (patch) | |
| tree | 235bb46afaee00d5f97090d6e32fb779174d518c /arch/i386 | |
| parent | 7c72aaf29621d29ed19fd68c44edb45321645049 (diff) | |
[PATCH] kprobes: Fix return probes on sys_execve
Fix a bug in kprobes that can cause an Oops or even a crash when a return
probe is installed on one of the following functions: sys_execve,
do_execve, load_*_binary, flush_old_exec, or flush_thread. The fix is to
remove the call to kprobe_flush_task() in flush_thread(). This fix has
been tested on all architectures for which the return-probes feature has
been implemented (i386, x86_64, ppc64, ia64). Please apply.
BACKGROUND
Up to now, we have called kprobe_flush_task() under two situations: when a
task exits, and when it execs. Flushing kretprobe_instances on exit is
correct because (a) do_exit() doesn't return, and (b) one or more
return-probed functions may be active when a task calls do_exit(). Neither
is the case for sys_execve() and its callees.
Initially, the mistaken call to kprobe_flush_task() on exec was harmless
because we put the "real" return address of each active probed function
back in the stack, just to be safe, when we recycled its
kretprobe_instance. When support for ppc64 and ia64 was added, this safety
measure couldn't be employed, and was eventually dropped even for i386 and
x86_64. sys_execve() and its callees were informally blacklisted for
return probes until this fix was developed.
Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/i386')
| -rw-r--r-- | arch/i386/kernel/process.c | 7 |
1 files changed, 0 insertions, 7 deletions
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 1cb261f225d..df6c2bcde06 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -393,13 +393,6 @@ void flush_thread(void) { struct task_struct *tsk = current; - /* - * Remove function-return probe instances associated with this task - * and put them back on the free list. Do not insert an exit probe for - * this function, it will be disabled by kprobe_flush_task if you do. - */ - kprobe_flush_task(tsk); - memset(tsk->thread.debugreg, 0, sizeof(unsigned long)*8); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); /* |