> 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]>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review ยท https://sashiko.dev/#/patchset/178822361441.115597.11442662641658772793.stgit@devnote2?part=2
