On Tue, 1 Sep 2026 10:37:25 -0400 Steven Rostedt <[email protected]> wrote:
> On Tue, 1 Sep 2026 23:21:49 +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]> > > Reviewed-by: Steven Rostedt <[email protected]> Thanks! Let me pick those to probes/fixes. > > -- Steve -- Masami Hiramatsu (Google) <[email protected]>
