Commit-ID: 27747f8bc355a2808ca9e490ab6866acd85b4c16 Gitweb: http://git.kernel.org/tip/27747f8bc355a2808ca9e490ab6866acd85b4c16 Author: Andy Lutomirski <luto@xxxxxxxxxx> AuthorDate: Thu, 30 Jul 2015 20:32:42 -0700 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 4 Aug 2015 10:16:55 +0200 perf/x86/hw_breakpoints: Fix check for kernel-space breakpoints The check looked wrong, although I think it was actually safe. TASK_SIZE is unnecessarily small for compat tasks, and it wasn't possible to make a range breakpoint so large it started in user space and ended in kernel space. Nonetheless, let's fix up the check for the benefit of future readers. A breakpoint is in the kernel if either end is in the kernel. Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/136be387950e78f18cea60e9d1bef74465d0ee8f.1438312874.git.luto@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- arch/x86/kernel/hw_breakpoint.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 6f345d3..50a3fad 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -180,7 +180,11 @@ int arch_check_bp_in_kernelspace(struct perf_event *bp) va = info->address; len = bp->attr.bp_len; - return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); + /* + * We don't need to worry about va + len - 1 overflowing: + * we already require that va is aligned to a multiple of len. + */ + return (va >= TASK_SIZE_MAX) || ((va + len - 1) >= TASK_SIZE_MAX); } int arch_bp_generic_fields(int x86_len, int x86_type, -- 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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