From: Donggeun Yoo <donggeunyoo.kernel@gmail.com> stable inclusion from stable-v6.6.158 commit 98da3379cdee343f671dac89b9afbd8b071f2591 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/20177 CVE: CVE-2026-97936 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit a5e70ba87ca8ebc79b4e63de302d03b0625fe153 upstream. parse_field() sets HIST_FIELD_FL_STACKTRACE from the ".stacktrace" modifier before it looks the field name up, and nothing afterwards checks that the name resolved to a field which holds a stacktrace. create_hist_field() picks HIST_FIELD_FN_STACK on the strength of the field pointer alone, which reads a __data_loc word from the record and follows its low 16 bits as an offset into the same record. event_hist_trigger() takes the first word there as an entry count and copies that many longs into a 31 entry array: n_entries = *stack; memcpy(entries, ++stack, n_entries * sizeof(unsigned long)); Neither end of that copy is bounded, and the count is whatever the event holds at the offset, so any field will do: # cd /sys/kernel/tracing/events/sched/sched_process_fork # echo 'hist:keys=parent_pid.stacktrace' > trigger # (true) BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: 0010:rb_insert_color+0x18/0x130 timerqueue_linked_add+0x7e/0xd0 enqueue_hrtimer+0x39/0xb0 __hrtimer_run_queues+0x10f/0x1f0 </IRQ> RIP: 0010:memcpy+0xc/0x30 event_hist_trigger+0x165/0x690 The timer interrupt landed on the rbtree the copy had already run over. No debug options are needed for this; KASAN reports the same write as an out-of-bounds read of 13835058055416381440 bytes. Documentation/trace/histogram.rst already states the rule, "must be a long[] type", so enforce it once the name has been resolved. Names which resolve to no field at all, "hitcount.stacktrace" and the common_* pseudo-fields, are refused for the same reason: they hold no stacktrace to read. Cc: stable@vger.kernel.org Fixes: cc5fc8bfc961 ("tracing/histogram: Add stacktrace type") Link: https://patch.msgid.link/20260907155045.692664-2-donggeunyoo.kernel@gmail.co... Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tengda Wu <wutengda2@huawei.com> --- kernel/trace/trace_events_hist.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 856d75942581..5d448e5aedfe 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -2318,6 +2318,7 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file, struct ftrace_event_field *field = NULL; char *field_name, *modifier, *str; struct trace_array *tr = file->tr; + bool stack_modifier = false; modifier = str = kstrdup(field_str, GFP_KERNEL); if (!modifier) @@ -2340,9 +2341,10 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file, *flags |= HIST_FIELD_FL_EXECNAME; else if (strcmp(modifier, "syscall") == 0) *flags |= HIST_FIELD_FL_SYSCALL; - else if (strcmp(modifier, "stacktrace") == 0) + else if (strcmp(modifier, "stacktrace") == 0) { *flags |= HIST_FIELD_FL_STACKTRACE; - else if (strcmp(modifier, "log2") == 0) + stack_modifier = true; + } else if (strcmp(modifier, "log2") == 0) *flags |= HIST_FIELD_FL_LOG2; else if (strcmp(modifier, "usecs") == 0) *flags |= HIST_FIELD_FL_TIMESTAMP_USECS; @@ -2410,6 +2412,12 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file, } } } + + if (stack_modifier && + (!field || field->filter_type != FILTER_STACKTRACE)) { + hist_err(tr, HIST_ERR_BAD_FIELD_MODIFIER, errpos(field_str)); + field = ERR_PTR(-EINVAL); + } out: kfree(str); -- 2.34.1