Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] Blindly duplicating all eh_frame sections ignores VMA inheritance rules (e.g., VM_DONTCOPY), leading to stale unwinding data. - [Medium] Mixing goto-based error handling with guard() cleanup in the same function. --
--- Patch [15]: [RFC PATCH v2 15/24] unwind_user/eh_frame: Duplicate registered .eh_frame[_hdr] section data on clone/fork --- commit cedc4c84b3351e03d89a9e7fc338f35818891c5a Author: Jens Remus <[email protected]> unwind_user/eh_frame: Duplicate registered .eh_frame[_hdr] section data on clone/fork When duplicating a process' virtual memory mappings also duplicate all of its registered .eh_frame_hdr sections stored in the per-mm maple tree to enable stacktracing using eh_frame of the child process. > diff --git a/kernel/unwind/eh_frame.c b/kernel/unwind/eh_frame.c > index b0be56e315080..1ac7308814a16 100644 > --- a/kernel/unwind/eh_frame.c > +++ b/kernel/unwind/eh_frame.c [ ... ] > @@ -1501,6 +1501,54 @@ int eh_frame_remove_section(unsigned long > eh_frame_hdr_start) > return 0; > } > > +static void __eh_frame_dup_section(struct eh_frame_section *sec, > + struct eh_frame_section *oldsec) > +{ [ ... ] > +} > + > +int eh_frame_dup_mm(struct mm_struct *mm, struct mm_struct *oldmm) > +{ > + struct eh_frame_section *sec, *oldsec; > + unsigned long index = 0; > + int ret; > + > + guard(srcu)(&eh_frame_srcu); [Severity: Medium] Is it acceptable to mix goto-based error handling with guard() in the same function? The cleanup guidelines suggest converting all resources to scope-based cleanup or none to avoid confusing ownership semantics. > + > + mt_for_each(&oldmm->eh_frame_mt, oldsec, index, ULONG_MAX) { [Severity: High] Does this unconditionally duplicate all eh_frame sections from the parent without checking if the underlying VMA was actually copied during the fork? If a process sets a region to VM_DONTCOPY or VM_WIPEONFORK before forking, the child won't inherit the VMA, but it appears it will still inherit the eh_frame section here. If the child process later maps new executable code at the same address, could the unwinder use the parent's stale rules? > + sec = kzalloc(sizeof(*sec), GFP_KERNEL_ACCOUNT); > + if (!sec) > + return -ENOMEM; > + > + __eh_frame_dup_section(sec, oldsec); > + > + ret = mtree_insert_range(&mm->eh_frame_mt, > + sec->text_start, > + sec->text_end - 1, > + sec, GFP_KERNEL_ACCOUNT); > + if (ret) > + goto err_free; > + } > + > + return 0; > + > +err_free: > + free_section(sec); > + return ret; > +} -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=15
