[patch 05/29] oProfile: oops when profile_pc() returns ~0LU

Greg Kroah-Hartman
2007-11-20T18:27:35Z

[-- Attachment #1: oprofile-oops-when-profile_pc-returns-0lu.patch --]
[-- Type: text/plain, Size: 2726 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Philippe Elie <phil.el@wanadoo.fr>

patch df9d177aa28d50e64bae6fbd6b263833079e3571 in mainline.

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 <phil.el@wanadoo.fr>
Tested-by: Sami Farin <safari-kernel@safari.iki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/oprofile/cpu_buffer.c | 7 +++++++
drivers/oprofile/cpu_buffer.h | 1 +
drivers/oprofile/oprofile_stats.c | 4 ++++
3 files changed, 12 insertions(+)

--- 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_cp

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;
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -42,6 +42,7 @@ struct oprofile_cpu_buffer {
unsigned long sample_received;
unsigned long sample_lost_overflow;
unsigned long backtrace_aborted;
+ unsigned long sample_invalid_eip;
int cpu;
struct delayed_work work;
} ____cacheline_aligned;
--- a/drivers/oprofile/oprofile_stats.c
+++ b/drivers/oprofile/oprofile_stats.c
@@ -26,6 +26,8 @@ void oprofile_reset_stats(void)
cpu_buf = &cpu_buffer[i];
cpu_buf->sample_received = 0;
cpu_buf->sample_lost_overflow = 0;
+ cpu_buf->backtrace_aborted = 0;
+ cpu_buf->sample_invalid_eip = 0;
}

atomic_set(&oprofile_stats.sample_lost_no_mm, 0);
@@ -61,6 +63,8 @@ void oprofile_create_stats_files(struct
&cpu_buf->sample_lost_overflow);
oprofilefs_create_ro_ulong(sb, cpudir, "backtrace_aborted",
&cpu_buf->backtrace_aborted);
+ oprofilefs_create_ro_ulong(sb, cpudir, "sample_invalid_eip",
+ &cpu_buf->sample_invalid_eip);
}

oprofilefs_create_ro_atomic(sb, dir, "sample_lost_no_mm",

--