| Message ID | 1303478187-2367-1-git-send-email-fweisbec@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Fri, Apr 22, 2011 at 03:16:27PM +0200, Frederic Weisbecker wrote: > (resend with ppc list in cc) > > While the tracer accesses ptrace breakpoints, the child task may > concurrently exit due to a SIGKILL and thus release its breakpoints > at the same time. We can then dereference some freed pointers. > > To fix this, hold a reference on the child breakpoints before > manipulating them. > > Reported-by: Oleg Nesterov <oleg@redhat.com> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Prasad <prasad@linux.vnet.ibm.com> > Cc: Paul Mundt <lethal@linux-sh.org> > Cc: v2.6.33.. <stable@kernel.org> > --- > arch/powerpc/kernel/ptrace.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c > index 55613e3..4edeeb3 100644 > --- a/arch/powerpc/kernel/ptrace.c > +++ b/arch/powerpc/kernel/ptrace.c > @@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long request, > } > > case PTRACE_SET_DEBUGREG: > + if (ptrace_get_breakpoints(child) < 0) > + return -ESRCH; > ret = ptrace_set_debugreg(child, addr, data); > + ptrace_put_breakpoints(child); > break; > > #ifdef CONFIG_PPC64 > -- > 1.7.3.2 > Hi Frederic, Looks fine to me. Acked-by: K.Prasad <prasad@linux.vnet.ibm.com> Thanks, K.Prasad
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 55613e3..4edeeb3 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -1591,7 +1591,10 @@ long arch_ptrace(struct task_struct *child, long request, } case PTRACE_SET_DEBUGREG: + if (ptrace_get_breakpoints(child) < 0) + return -ESRCH; ret = ptrace_set_debugreg(child, addr, data); + ptrace_put_breakpoints(child); break; #ifdef CONFIG_PPC64
(resend with ppc list in cc) While the tracer accesses ptrace breakpoints, the child task may concurrently exit due to a SIGKILL and thus release its breakpoints at the same time. We can then dereference some freed pointers. To fix this, hold a reference on the child breakpoints before manipulating them. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Will Deacon <will.deacon@arm.com> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: v2.6.33.. <stable@kernel.org> --- arch/powerpc/kernel/ptrace.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)