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authorFrederic Weisbecker <fweisbec@gmail.com>2011-04-08 17:29:36 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2011-04-25 17:35:18 +0200
commitbf0b8f4b55e591ba417c2dbaff42769e1fc773b0 (patch)
tree4d70fa98ef40860ff596fccb05518c1806697a39 /arch/arm/kernel/ptrace.c
parent07fa7a0a8a586c01a8b416358c7012dcb9dc688d (diff)
arm, hw_breakpoints: Fix racy access to ptrace breakpoints
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> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Prasad <prasad@linux.vnet.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Link: http://lkml.kernel.org/r/1302284067-7860-5-git-send-email-fweisbec@gmail.com
Diffstat (limited to 'arch/arm/kernel/ptrace.c')
-rw-r--r--arch/arm/kernel/ptrace.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 2bf27f364d09..8182f45ca493 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -767,12 +767,20 @@ long arch_ptrace(struct task_struct *child, long request,
#ifdef CONFIG_HAVE_HW_BREAKPOINT
case PTRACE_GETHBPREGS:
+ if (ptrace_get_breakpoints(child) < 0)
+ return -ESRCH;
+
ret = ptrace_gethbpregs(child, addr,
(unsigned long __user *)data);
+ ptrace_put_breakpoints(child);
break;
case PTRACE_SETHBPREGS:
+ if (ptrace_get_breakpoints(child) < 0)
+ return -ESRCH;
+
ret = ptrace_sethbpregs(child, addr,
(unsigned long __user *)data);
+ ptrace_put_breakpoints(child);
break;
#endif