On Wed, Dec 30, 2020 at 5:09 AM Nicolas Iooss <nicolas.iooss@xxxxxxx> wrote: > > OSS-Fuzz found a heap buffer overflow (out-of-bound reads) when the CIL > compiler tries to report a recursive blockinherit with an optional > block: > > $ echo '(block b (optional o (blockinherit b)))' > tmp.cil > $ secilc tmp.cil > Segmentation fault (core dumped) > > This is because cil_print_recursive_blockinherit() assumes that all > nodes are either CIL_BLOCK or CIL_BLOCKINHERIT. Add support for other > block kinds, using cil_node_to_string() to show them. > > Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28462 > Signed-off-by: Nicolas Iooss <nicolas.iooss@xxxxxxx> Acked-by: James Carter <jwcart2@xxxxxxxxx> > --- > libsepol/cil/src/cil_resolve_ast.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/libsepol/cil/src/cil_resolve_ast.c b/libsepol/cil/src/cil_resolve_ast.c > index f6deb1002fbd..ecd05dfa5dab 100644 > --- a/libsepol/cil/src/cil_resolve_ast.c > +++ b/libsepol/cil/src/cil_resolve_ast.c > @@ -2343,11 +2343,13 @@ void cil_print_recursive_blockinherit(struct cil_tree_node *bi_node, struct cil_ > for (curr = bi_node; curr != terminating_node; curr = curr->parent) { > if (curr->flavor == CIL_BLOCK) { > cil_list_prepend(trace, CIL_NODE, curr); > - } else { > + } else if (curr->flavor == CIL_BLOCKINHERIT) { > if (curr != bi_node) { > cil_list_prepend(trace, CIL_NODE, NODE(((struct cil_blockinherit *)curr->data)->block)); > } > cil_list_prepend(trace, CIL_NODE, curr); > + } else { > + cil_list_prepend(trace, CIL_NODE, curr); > } > } > cil_list_prepend(trace, CIL_NODE, terminating_node); > @@ -2356,8 +2358,12 @@ void cil_print_recursive_blockinherit(struct cil_tree_node *bi_node, struct cil_ > curr = item->data; > if (curr->flavor == CIL_BLOCK) { > cil_tree_log(curr, CIL_ERR, "block %s", DATUM(curr->data)->name); > - } else { > + } else if (curr->flavor == CIL_BLOCKINHERIT) { > cil_tree_log(curr, CIL_ERR, "blockinherit %s", ((struct cil_blockinherit *)curr->data)->block_str); > + } else if (curr->flavor == CIL_OPTIONAL) { > + cil_tree_log(curr, CIL_ERR, "optional %s", DATUM(curr->data)->name); > + } else { > + cil_tree_log(curr, CIL_ERR, "%s", cil_node_to_string(curr)); > } > } > > -- > 2.29.2 >
