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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 <phil.el@wanadoo.fr>
Tested-by: Sami Farin <safari-kernel@safari.iki.fi>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Philippe Elie 2007-11-14 16:58:48 -08:00 committed by Linus Torvalds
parent 03ad369ac9
commit df9d177aa2
3 changed files with 12 additions and 0 deletions
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7
drivers/oprofile/cpu_buffer.c
View File

@ -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;

1
drivers/oprofile/cpu_buffer.h
View File

@ -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;

4
drivers/oprofile/oprofile_stats.c
View File

@ -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 super_block * sb, struct dentry * root)
&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",