* [PATCH] cgroup: align the comm length with TASK_COMM_LEN
@ 2022-09-20 8:49 Kassey Li
2022-09-22 0:33 ` Kassey Li
0 siblings, 1 reply; 2+ messages in thread
From: Kassey Li @ 2022-09-20 8:49 UTC (permalink / raw)
To: rostedt, mingo, tj, william.kucharski; +Cc: Kassey Li, linux-kernel
__string could get a dst string with length less than
TASK_COMM_LEN.
a task->comm possbile change dynamic that can cause
out of bounds access for the dst string buffer.
change it as arrary with same length TASK_COMM_LEN,
this aligns the same usage of include/trace on task->comm.
Signed-off-by: Kassey Li <quic_yingangl@quicinc.com>
---
include/trace/events/cgroup.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
index dd7d7c9efecd..d0c5f93e3611 100644
--- a/include/trace/events/cgroup.h
+++ b/include/trace/events/cgroup.h
@@ -130,7 +130,7 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
__field( u64, dst_id )
__field( int, pid )
__string( dst_path, path )
- __string( comm, task->comm )
+ __array(char, comm, TASK_COMM_LEN)
),
TP_fast_assign(
@@ -139,12 +139,12 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
__entry->dst_level = dst_cgrp->level;
__assign_str(dst_path, path);
__entry->pid = task->pid;
- __assign_str(comm, task->comm);
+ memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
),
TP_printk("dst_root=%d dst_id=%llu dst_level=%d dst_path=%s pid=%d comm=%s",
__entry->dst_root, __entry->dst_id, __entry->dst_level,
- __get_str(dst_path), __entry->pid, __get_str(comm))
+ __get_str(dst_path), __entry->pid, __entry->comm)
);
DEFINE_EVENT(cgroup_migrate, cgroup_attach_task,
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] cgroup: align the comm length with TASK_COMM_LEN
2022-09-20 8:49 [PATCH] cgroup: align the comm length with TASK_COMM_LEN Kassey Li
@ 2022-09-22 0:33 ` Kassey Li
0 siblings, 0 replies; 2+ messages in thread
From: Kassey Li @ 2022-09-22 0:33 UTC (permalink / raw)
To: rostedt, mingo, tj, william.kucharski; +Cc: linux-kernel
hello:
here is the instance of the problem：
may you kindly review this change ?
Unable to handle kernel write to read-only memory at virtual address
ffffffbcf7450000
Call trace:
dump_backtrace.cfi_jt+0x0/0x4
show_stack+0x14/0x1c
dump_stack+0xa0/0xd8
die_callback+0x248/0x24c
notify_die+0x7c/0xf8
die+0xac/0x290
die_kernel_fault+0x88/0x98
die_kernel_fault+0x0/0x98
do_page_fault+0xa0/0x544
do_mem_abort+0x60/0x10c
el1_da+0x1c/0xc4
trace_event_raw_event_cgroup_migrate+0x124/0x170
cgroup_attach_task+0x2e8/0x41c
__cgroup1_procs_write+0x114/0x1ec
cgroup1_tasks_write+0x10/0x18
cgroup_file_write+0xa4/0x208
kernfs_fop_write+0x1f0/0x2f4
__vfs_write+0x5c/0x200
vfs_write+0xe0/0x1a0
ksys_write+0x74/0xdc
__arm64_sys_write+0x18/0x20
el0_svc_common+0xc0/0x1a4
el0_svc_compat_handler+0x18/0x20
el0_svc_compat+0x8/0x2c
On 9/20/2022 4:49 PM, Kassey Li wrote:
> __string could get a dst string with length less than
> TASK_COMM_LEN.
>
> a task->comm possbile change dynamic that can cause
> out of bounds access for the dst string buffer.
>
> change it as arrary with same length TASK_COMM_LEN,
> this aligns the same usage of include/trace on task->comm.
>
> Signed-off-by: Kassey Li <quic_yingangl@quicinc.com>
> ---
> include/trace/events/cgroup.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/trace/events/cgroup.h b/include/trace/events/cgroup.h
> index dd7d7c9efecd..d0c5f93e3611 100644
> --- a/include/trace/events/cgroup.h
> +++ b/include/trace/events/cgroup.h
> @@ -130,7 +130,7 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
> __field( u64, dst_id )
> __field( int, pid )
> __string( dst_path, path )
> - __string( comm, task->comm )
> + __array(char, comm, TASK_COMM_LEN)
> ),
>
> TP_fast_assign(
> @@ -139,12 +139,12 @@ DECLARE_EVENT_CLASS(cgroup_migrate,
> __entry->dst_level = dst_cgrp->level;
> __assign_str(dst_path, path);
> __entry->pid = task->pid;
> - __assign_str(comm, task->comm);
> + memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
> ),
>
> TP_printk("dst_root=%d dst_id=%llu dst_level=%d dst_path=%s pid=%d comm=%s",
> __entry->dst_root, __entry->dst_id, __entry->dst_level,
> - __get_str(dst_path), __entry->pid, __get_str(comm))
> + __get_str(dst_path), __entry->pid, __entry->comm)
> );
>
> DEFINE_EVENT(cgroup_migrate, cgroup_attach_task,
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-09-22 0:33 ` Kassey Li
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