The follow commands caused a crash:
# cd /sys/kernel/tracing
# echo 's:open char file[]' > dynamic_events
# echo 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)' > events/syscalls/sys_enter_openat/trigger'
# echo 1 > events/synthetic/open/enable
BOOM!
The problem is that the synthetic event field "char file[]" will read
the value given to it as a string without any memory checks to make sure
the address is valid. The above example will pass in the user space
address and the sythetic event code will happily call strlen() on it
and then strscpy() where either one will cause an oops when accessing
user space addresses.
Changes since v1: https://lore.kernel.org/all/[email protected]/
- Handle "(fault)" printing when there's a fault
Steven Rostedt (Google) (3):
tracing: Move duplicate code of trace_kprobe/eprobe.c into header
tracing: Add "(fault)" name injection to kernel probes
tracing: Fix reading strings from synthetic events
----
kernel/trace/trace_eprobe.c | 60 ++------------------
kernel/trace/trace_events_synth.c | 23 ++++++--
kernel/trace/trace_kprobe.c | 60 ++------------------
kernel/trace/trace_probe_kernel.h | 115 ++++++++++++++++++++++++++++++++++++++
4 files changed, 142 insertions(+), 116 deletions(-)
create mode 100644 kernel/trace/trace_probe_kernel.h
Hi,
2022年10月12日(水) 11:45 Steven Rostedt <[email protected]>:
>
>
> The follow commands caused a crash:
>
> # cd /sys/kernel/tracing
> # echo 's:open char file[]' > dynamic_events
> # echo 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)' > events/syscalls/sys_enter_openat/trigger'
> # echo 1 > events/synthetic/open/enable
>
> BOOM!
>
> The problem is that the synthetic event field "char file[]" will read
> the value given to it as a string without any memory checks to make sure
> the address is valid. The above example will pass in the user space
> address and the sythetic event code will happily call strlen() on it
> and then strscpy() where either one will cause an oops when accessing
> user space addresses.
>
> Changes since v1: https://lore.kernel.org/all/[email protected]/
Thanks, this series of patches looks good to me.
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Thank you!
>
> - Handle "(fault)" printing when there's a fault
>
> Steven Rostedt (Google) (3):
> tracing: Move duplicate code of trace_kprobe/eprobe.c into header
> tracing: Add "(fault)" name injection to kernel probes
> tracing: Fix reading strings from synthetic events
>
> ----
> kernel/trace/trace_eprobe.c | 60 ++------------------
> kernel/trace/trace_events_synth.c | 23 ++++++--
> kernel/trace/trace_kprobe.c | 60 ++------------------
> kernel/trace/trace_probe_kernel.h | 115 ++++++++++++++++++++++++++++++++++++++
> 4 files changed, 142 insertions(+), 116 deletions(-)
> create mode 100644 kernel/trace/trace_probe_kernel.h
--
Masami Hiramatsu
mailto:[email protected]
Hi Steve,
On Wed, 2022-10-12 at 06:40 -0400, Steven Rostedt wrote:
>
> The follow commands caused a crash:
>
> # cd /sys/kernel/tracing
> # echo 's:open char file[]' > dynamic_events
> # echo
> 'hist:keys=common_pid:file=filename:onchange($file).trace(open,$file)
> ' > events/syscalls/sys_enter_openat/trigger'
> # echo 1 > events/synthetic/open/enable
>
> BOOM!
>
> The problem is that the synthetic event field "char file[]" will read
> the value given to it as a string without any memory checks to make
> sure
> the address is valid. The above example will pass in the user space
> address and the sythetic event code will happily call strlen() on it
> and then strscpy() where either one will cause an oops when accessing
> user space addresses.
>
> Changes since v1:
> https://lore.kernel.org/all/[email protected]/
>
> - Handle "(fault)" printing when there's a fault
Thanks for fixing the synthetic event string tracing bug, along with
the other nice cleanup.
Reviewed-by: Tom Zanussi <[email protected]>
>
> Steven Rostedt (Google) (3):
> tracing: Move duplicate code of trace_kprobe/eprobe.c into
> header
> tracing: Add "(fault)" name injection to kernel probes
> tracing: Fix reading strings from synthetic events
>
> ----
> kernel/trace/trace_eprobe.c | 60 ++------------------
> kernel/trace/trace_events_synth.c | 23 ++++++--
> kernel/trace/trace_kprobe.c | 60 ++------------------
> kernel/trace/trace_probe_kernel.h | 115
> ++++++++++++++++++++++++++++++++++++++
> 4 files changed, 142 insertions(+), 116 deletions(-)
> create mode 100644 kernel/trace/trace_probe_kernel.h