On Fri, Feb 5, 2021 at 4:54 AM Nicolas Iooss <nicolas.iooss@xxxxxxx> wrote: > > OSS-Fuzz found a Null-dereference READ in the CIL compiler when trying > to compile the following policy: > > (macro m((name n))) (call m(())) > > When calling the macro, the name (in variable "pc") is NULL, which > triggers a NULL pointer dereference when using it as a key in > __cil_insert_name(). The stack trace is: > > #0 0x7f4662655a85 in __strlen_avx2 (/usr/lib/libc.so.6+0x162a85) > #1 0x556d0b6d150c in __interceptor_strlen.part.0 (/selinux/libsepol/fuzz/fuzz-secilc+0x44850c) > #2 0x556d0ba74ed6 in symhash /selinux/libsepol/src/symtab.c:22:9 > #3 0x556d0b9ef50d in hashtab_search /selinux/libsepol/src/hashtab.c:186:11 > #4 0x556d0b928e1f in cil_symtab_get_datum /selinux/libsepol/src/../cil/src/cil_symtab.c:121:37 > #5 0x556d0b8f28f4 in __cil_insert_name /selinux/libsepol/src/../cil/src/cil_resolve_ast.c:96:2 > #6 0x556d0b908184 in cil_resolve_call1 /selinux/libsepol/src/../cil/src/cil_resolve_ast.c:2835:12 > #7 0x556d0b91b404 in __cil_resolve_ast_node /selinux/libsepol/src/../cil/src/cil_resolve_ast.c > #8 0x556d0b91380f in __cil_resolve_ast_node_helper /selinux/libsepol/src/../cil/src/cil_resolve_ast.c:3773:7 > #9 0x556d0b932230 in cil_tree_walk_core /selinux/libsepol/src/../cil/src/cil_tree.c:263:9 > #10 0x556d0b932230 in cil_tree_walk /selinux/libsepol/src/../cil/src/cil_tree.c:307:7 > #11 0x556d0b932326 in cil_tree_walk_core /selinux/libsepol/src/../cil/src/cil_tree.c:275:9 > #12 0x556d0b932326 in cil_tree_walk /selinux/libsepol/src/../cil/src/cil_tree.c:307:7 > #13 0x556d0b911189 in cil_resolve_ast /selinux/libsepol/src/../cil/src/cil_resolve_ast.c:3941:8 > #14 0x556d0b798729 in cil_compile /selinux/libsepol/src/../cil/src/cil.c:550:7 > > Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28544 > Signed-off-by: Nicolas Iooss <nicolas.iooss@xxxxxxx> Wow, that function is getting long and ugly. It probably needs to be refactored at some point. At any rate, your patch is good. Acked-by: James Carter <jwcart2@xxxxxxxxx> > --- > libsepol/cil/src/cil_resolve_ast.c | 79 ++++++++++++++++++++++++++++++ > 1 file changed, 79 insertions(+) > > diff --git a/libsepol/cil/src/cil_resolve_ast.c b/libsepol/cil/src/cil_resolve_ast.c > index 0c85eabe5a81..9300cd2be9be 100644 > --- a/libsepol/cil/src/cil_resolve_ast.c > +++ b/libsepol/cil/src/cil_resolve_ast.c > @@ -2828,6 +2828,12 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > switch (flavor) { > case CIL_NAME: { > struct cil_name *name; > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > name = __cil_insert_name(args->db, pc->data, current); > if (name != NULL) { > new_arg->arg = (struct cil_symtab_datum *)name; > @@ -2837,21 +2843,57 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > } > break; > case CIL_TYPE: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_ROLE: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_USER: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_SENS: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_CAT: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_BOOL: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_CATSET: { > @@ -2871,6 +2913,11 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > cil_list_append(((struct cil_symtab_datum*)catset)->nodes, > CIL_LIST_ITEM, cat_node); > new_arg->arg = (struct cil_symtab_datum*)catset; > + } else if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > } else { > new_arg->arg_str = pc->data; > } > @@ -2896,6 +2943,11 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > cil_list_append(((struct cil_symtab_datum*)level)->nodes, > CIL_LIST_ITEM, lvl_node); > new_arg->arg = (struct cil_symtab_datum*)level; > + } else if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > } else { > new_arg->arg_str = pc->data; > } > @@ -2921,6 +2973,11 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > cil_list_append(((struct cil_symtab_datum*)range)->nodes, > CIL_LIST_ITEM, range_node); > new_arg->arg = (struct cil_symtab_datum*)range; > + } else if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > } else { > new_arg->arg_str = pc->data; > } > @@ -2946,6 +3003,11 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > cil_list_append(((struct cil_symtab_datum*)ipaddr)->nodes, > CIL_LIST_ITEM, addr_node); > new_arg->arg = (struct cil_symtab_datum*)ipaddr; > + } else if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > } else { > new_arg->arg_str = pc->data; > } > @@ -2953,9 +3015,21 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > break; > } > case CIL_CLASS: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_MAP_CLASS: > + if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > + } > new_arg->arg_str = pc->data; > break; > case CIL_CLASSPERMISSION: { > @@ -2976,6 +3050,11 @@ int cil_resolve_call1(struct cil_tree_node *current, void *extra_args) > cp_node->data = cp; > cil_list_append(cp->datum.nodes, CIL_LIST_ITEM, cp_node); > new_arg->arg = (struct cil_symtab_datum*)cp; > + } else if (pc->data == NULL) { > + cil_tree_log(current, CIL_ERR, "Invalid macro parameter"); > + cil_destroy_args(new_arg); > + rc = SEPOL_ERR; > + goto exit; > } else { > new_arg->arg_str = pc->data; > } > -- > 2.30.0 >
