On Thu, 3 Jul 2025 13:26:35 +0900 "Masami Hiramatsu (Google)" <[email protected]> wrote:
> From: Masami Hiramatsu (Google) <[email protected]> > > With CONFIG_DEBUG_INFO_BTF=y and PAHOLE_HAS_BTF_TAG=y, `__user` is > converted to `__attribute((btf_type_tag("user")))`. In this case, > some syscall events have `const char __attribute(...) *` for __user > string, like below; > > /sys/kernel/tracing # cat events/syscalls/sys_enter_openat/format > name: sys_enter_openat > ID: 720 > format: > field:unsigned short common_type; offset:0; size:2; > signed:0; > field:unsigned char common_flags; offset:2; size:1; > signed:0; > field:unsigned char common_preempt_count; offset:3; size:1; > signed:0; > field:int common_pid; offset:4; size:4; signed:1; > > field:int __syscall_nr; offset:8; size:4; signed:1; > field:int dfd; offset:16; size:8; signed:0; > field:const char __attribute__((btf_type_tag("user"))) * filename; > offset:24; Ahh, sorry, it was "__attribute__()" not "__attribute()". Anyway, I think we should sanitize the __attribute__ from format. Thank you, size:8; signed:0; > field:int flags; offset:32; size:8; signed:0; > field:umode_t mode; offset:40; size:8; signed:0; > > > Then the trace event filter failes to set string acceptable flag > (FILTER_PTR_STRING) and rejects setting string filter; > > # echo 'filename.ustring ~ "*ftracetest-dir.wbx24v*"' >> > events/syscalls/sys_enter_openat/filter > sh: write error: Invalid argument > # cat error_log > [ 723.743637] event filter parse error: error: Expecting numeric field > Command: filename.ustring ~ "*ftracetest-dir.wbx24v*" > > Handle "(const) char __attribute() *" also as string ptr type. > > Signed-off-by: Masami Hiramatsu (Google) <[email protected]> > --- > kernel/trace/trace_events_filter.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/kernel/trace/trace_events_filter.c > b/kernel/trace/trace_events_filter.c > index 3885aadc434d..5e27190a0377 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -1488,6 +1488,11 @@ int filter_assign_type(const char *type) > if (strcmp(type, "char *") == 0 || strcmp(type, "const char *") == 0) > return FILTER_PTR_STRING; > > + /* Ignore attributes */ > + if (glob_match("char __attribute(*) \\*", type) || > + glob_match("const char __attribute(*) \\*", type)) > + return FILTER_PTR_STRING; > + > return FILTER_OTHER; > } > > -- Masami Hiramatsu (Google) <[email protected]>
