Fix use-after-free SEGV on RS274-X export (#162)#379
Merged
spe-ciellt merged 1 commit intogerbv:developfrom Mar 7, 2026
Merged
Fix use-after-free SEGV on RS274-X export (#162)#379spe-ciellt merged 1 commit intogerbv:developfrom
spe-ciellt merged 1 commit intogerbv:developfrom
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gerbv_image_duplicate_layer() and gerbv_image_duplicate_state() do a shallow struct copy which retains the original's next pointer. When the original image is freed during export, the duplicate's next pointer becomes dangling. Freeing the duplicate then follows the dangling pointer and crashes. NULL the next pointer after the shallow copy in both functions. Callers in gerbv_image_duplicate_image() already wire up their own next chain, so the only element affected is the last in each list, which must be NULL anyway.
This was referenced Mar 7, 2026
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Summary
Fixes #162 — use-after-free crash when exporting a file as RS274-X.
gerbv_image_duplicate_layer()andgerbv_image_duplicate_state()shallow-copy their input structs, which retains the original'snextpointer. When the original image is freed during export the duplicate'snextbecomes dangling, and freeing the duplicate follows it into freed memory.The fix NULLs
nextafter the shallow copy in both functions. Callers ingerbv_image_duplicate_image()already build their own linked-list chain vialastLayer->next = gerbv_image_duplicate_layer(...), so the duplicates'nextpointers are always overwritten — except for the last element, which must be NULL.Changes
src/gerb_image.c: AddnewLayer->next = NULLingerbv_image_duplicate_layer()src/gerb_image.c: AddnewState->next = NULLingerbv_image_duplicate_state()Test plan
cmake --preset linux-gnu-gcc && cmake --build buildgerbv --export=rs274x --output=out.grb input.grbno longer crashes (reproducer from SEGV on export file as RS274-X #162)