From b4c6edda4dc2e9d86c2dbd95a361032a7b956d1c Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Sun, 26 Apr 2026 15:59:38 +0200 Subject: [PATCH 8/8] apparmor: validate default DFA states are in bounds Some backports of commit 9063d7e2615f ("apparmor: validate DFA start states are in bounds in unpack_pdb") limited the bounds checks on DFA start states to the case where the start state was explicit in the policy. However, the default DFA start state (DFA_START = 1) could also be out-of-bounds. Move these checks out of the else-branches so that they are applied regardless of how the start state was initialised. Fixes: 5443c027ec16 ("apparmor: validate DFA start states are in bounds in unpack_pdb") Signed-off-by: Ben Hutchings --- security/apparmor/policy_unpack.c | 27 +++++++++++++++------------ 1 file changed, 15 insertions(+), 12 deletions(-) diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c index f0c5560e74cb..636fa078f00e 100644 --- a/security/apparmor/policy_unpack.c +++ b/security/apparmor/policy_unpack.c @@ -829,6 +829,8 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name) } if (aa_unpack_nameX(e, AA_STRUCT, "policydb")) { + size_t state_count; + /* generic policy dfa - optional and may be NULL */ info = "failed to unpack policydb"; profile->policy.dfa = unpack_dfa(e); @@ -843,13 +845,12 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name) if (!aa_unpack_u32(e, &profile->policy.start[0], "start")) { /* default start state */ profile->policy.start[0] = DFA_START; - } else { - size_t state_count = profile->policy.dfa->tables[YYTD_ID_BASE]->td_lolen; + } - if (profile->policy.start[0] >= state_count) { - info = "invalid dfa start state"; - goto fail; - } + state_count = profile->policy.dfa->tables[YYTD_ID_BASE]->td_lolen; + if (profile->policy.start[0] >= state_count) { + info = "invalid dfa start state"; + goto fail; } /* setup class index */ @@ -872,16 +873,18 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name) info = "failed to unpack profile file rules"; goto fail; } else if (profile->file.dfa) { + size_t state_count; + if (!aa_unpack_u32(e, &profile->file.start, "dfa_start")) { /* default start state */ profile->file.start = DFA_START; - } else { - size_t state_count = profile->file.dfa->tables[YYTD_ID_BASE]->td_lolen; + } - if (profile->file.start >= state_count) { - info = "invalid dfa start state"; - goto fail; - } + state_count = profile->file.dfa->tables[YYTD_ID_BASE]->td_lolen; + + if (profile->file.start >= state_count) { + info = "invalid dfa start state"; + goto fail; } } else if (profile->policy.dfa && profile->policy.start[AA_CLASS_FILE]) {