Fix SEGFAULT caused by out-of-bounds write #1124
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struct graph * is already available through g variable, let's use it directly.
Retrieve graph only when s->graph is already allocated, which also mens that the s->graph_width is bigger than 0, and thus avoid out-of-bounds write in graph_append function. Prior to 594d0c8 ("Fix bug of "Graph reset when using conditional color"") s->graph was not (re)allocated when s->graph_width and s->graph_allocated were equal to zero, therefore, s->graph stayed equal to nullptr. This effectively meant that graph_append function returned immediately after call and did nothing. This behavior changed with introduction of std::map<int, double *> graphs, because its retrieve_graph support function allocates s->graph even for s->graph_width equal to 0. Then, subsequent call of graph_append can continue and the first element of the graph is set later in this function in line: graph->graph[0] = f; /* add new data */ causing out-of-bounds write, as there is not enough space in array of zero length. This write messes up internal data of memory allocator (at least in musl libc case) and the application later segfaults in attempt to free this memory in store_graph function. Fixes: 594d0c8 ("Fix bug of "Graph reset when using conditional color"")
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Thanks and sorry for the delay! |
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No problem, thanks for merge! |
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This PR fixes
SEGFAULTcaused by out-of-bounds write which I was experiencing after update to newest version, see the commit message for broader explanation.I also replaced
graph_idvariable withg->idin other commit.