On Tue, 1 Sep 2026 09:04:42 -0400 Steven Rostedt <[email protected]> wrote:
> On Tue, 1 Sep 2026 09:47:17 +0900 > "Masami Hiramatsu (Google)" <[email protected]> wrote: > > > From: Masami Hiramatsu (Google) <[email protected]> > > > > btf_find_struct_member() traverses into nested anonymous structures and > > unions to find a struct member. However, get_bitoffset_of_field() in > > trace_probe.c checked btf_type_kflag(type) using the outer parent type > > instead of the actual anonymous structure/union that directly contains > > the found member. > > > > If the parent structure and anonymous structure have mismatched kflags > > (e.g., the parent has kflag=0 while the anonymous structure has kflag=1 > > because it contains bitfields), the bitfield size encoded in the upper > > 8 bits of member->offset is erroneously treated as part of the byte/bit > > offset, corrupting the resolved offset and failing to set last_bitsize. > > Similarly, btf_find_struct_member() pushed anonymous member offsets > > onto anon_stack without masking BTF_MEMBER_BIT_OFFSET() when kflag is set. > > > > To fix this problem, update btf_find_struct_member() to return actual > > containing structure/union type via member_type, use appropriate > > __btf_member_bit_offset() to get bit offset, and use member_type for > > btf_type_kflag() in get_bitoffset_of_field(). > > > > Fixes: c440adfbe302 ("tracing/probes: Support BTF based data structure > > field access") > > Cc: [email protected] > > Reported-by: Sashiko <[email protected]> > > Closes: > > https://lore.kernel.org/all/[email protected]/ > > Assisted-by: Antigravity:gemini-3.7-flash > > Signed-off-by: Masami Hiramatsu (Google) <[email protected]> > > --- > > > > @@ -661,11 +662,11 @@ static int get_bitoffset_of_field(char **pfieldname, > > const struct btf_type **pty > > ctx->last_bitsize = 0; > > } > > > > - type = btf_type_skip_modifiers(btf, field->type, NULL); > > - if (!type) { > > - trace_probe_log_err(ctx->offset, BAD_BTF_TID); > > - return -EINVAL; > > - } > > + type = btf_type_skip_modifiers(btf, field->type, NULL); > > + if (!type) { > > + trace_probe_log_err(ctx->offset, BAD_BTF_TID); > > + return -EINVAL; > > + } > > Is this just to fix the indentation? If so, can you make this a separate > patch? We don't need it to be part of a patch that gets backported. It may > make it more difficult to do so. OK, let me split it. Thanks, > > -- Steve > > > > > > if (next) > > ctx->offset += next - fieldname; > > -- Masami Hiramatsu (Google) <[email protected]>
