42 lines
1.5 KiB
Diff
42 lines
1.5 KiB
Diff
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From 38a09b74024bbe1c78639821f3cff3a5ceb73d0d Mon Sep 17 00:00:00 2001
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From: Nicolas Iooss <nicolas.iooss@m4x.org>
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Date: Wed, 30 Dec 2020 21:11:39 +0100
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Subject: [PATCH] libsepol/cil: fix NULL pointer dereference when using an
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unused alias
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OSS-Fuzz found a NULL pointer dereference when the CIL compiler tries to
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compile a policy where a categoryalias references an unused
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categoryalias:
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$ echo '(categoryalias c0)(categoryalias c1)(categoryaliasactual c0 c1)' > tmp.cil
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$ secil tmp.cil
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Segmentation fault (core dumped)
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In such a case, a1 can become NULL in cil_resolve_alias_to_actual().
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Add a check to report an error when this occurs. Now the error message
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is:
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Alias c0 references an unused alias c1 at tmp.cil:1
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Fixes: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28471
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Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
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---
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libsepol/cil/src/cil_resolve_ast.c | 4 ++++
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1 file changed, 4 insertions(+)
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diff --git a/libsepol/cil/src/cil_resolve_ast.c b/libsepol/cil/src/cil_resolve_ast.c
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index f6deb1002..affa7657b 100644
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--- a/libsepol/cil/src/cil_resolve_ast.c
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+++ b/libsepol/cil/src/cil_resolve_ast.c
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@@ -555,6 +555,10 @@ int cil_resolve_alias_to_actual(struct cil_tree_node *current, enum cil_flavor f
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a1_node = a1->datum.nodes->head->data;
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while (flavor != a1_node->flavor) {
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+ if (a1->actual == NULL) {
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+ cil_tree_log(current, CIL_ERR, "Alias %s references an unused alias %s", alias->datum.name, a1->datum.name);
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+ return SEPOL_ERR;
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+ }
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a1 = a1->actual;
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a1_node = a1->datum.nodes->head->data;
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steps += 1;
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