Commit-ID: 07fa7a0a8a586c01a8b416358c7012dcb9dc688d Gitweb: http://git.kernel.org/tip/07fa7a0a8a586c01a8b416358c7012dcb9dc688d Author: Frederic Weisbecker <fweisbec@xxxxxxxxx> AuthorDate: Fri, 8 Apr 2011 17:29:36 +0200 Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx> CommitDate: Mon, 25 Apr 2011 17:33:54 +0200 powerpc, 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@xxxxxxxxxx> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Acked-by: Prasad <prasad@xxxxxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: Paul Mundt <lethal@xxxxxxxxxxxx> Cc: v2.6.33.. <stable@xxxxxxxxxx> Link: http://lkml.kernel.org/r/1302284067-7860-4-git-send-email-fweisbec@xxxxxxxxx --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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