From df9d177aa28d50e64bae6fbd6b263833079e3571 Mon Sep 17 00:00:00 2001 From: Philippe Elie Date: Wed, 14 Nov 2007 16:58:48 -0800 Subject: oProfile: oops when profile_pc() returns ~0LU Instruction pointer returned by profile_pc() can be a random value. This break the assumption than we can safely set struct op_sample.eip field to a magic value to signal to the per-cpu buffer reader side special event like task switch ending up in a segfault in get_task_mm() when profile_pc() return ~0UL. Fixed by sanitizing the sampled eip and reject/log invalid eip. Problem reported by Sami Farin, patch tested by him. Signed-off-by: Philippe Elie Tested-by: Sami Farin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/oprofile/cpu_buffer.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/oprofile/cpu_buffer.c') diff --git a/drivers/oprofile/cpu_buffer.c b/drivers/oprofile/cpu_buffer.c index a83c3db7d18f..c93d3d2640ab 100644 --- a/drivers/oprofile/cpu_buffer.c +++ b/drivers/oprofile/cpu_buffer.c @@ -64,6 +64,8 @@ int alloc_cpu_buffers(void) b->head_pos = 0; b->sample_received = 0; b->sample_lost_overflow = 0; + b->backtrace_aborted = 0; + b->sample_invalid_eip = 0; b->cpu = i; INIT_DELAYED_WORK(&b->work, wq_sync_buffer); } @@ -175,6 +177,11 @@ static int log_sample(struct oprofile_cpu_buffer * cpu_buf, unsigned long pc, cpu_buf->sample_received++; + if (pc == ESCAPE_CODE) { + cpu_buf->sample_invalid_eip++; + return 0; + } + if (nr_available_slots(cpu_buf) < 3) { cpu_buf->sample_lost_overflow++; return 0; -- cgit v1.2.3