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| author | John Johansen <john.johansen@canonical.com> | 2020-03-30 23:37:54 -0700 |
|---|---|---|
| committer | John Johansen <john.johansen@canonical.com> | 2020-04-08 04:42:48 -0700 |
| commit | c27c6bd2c4d6b6bb779f9b722d5607993e1d5e5c (patch) | |
| tree | b7554ab191015fca33af785fc7affbf33fae7f91 /security/apparmor | |
| parent | 01df52d726b5d55d2970f5c957f1961930acd5d6 (diff) | |
| download | lwn-c27c6bd2c4d6b6bb779f9b722d5607993e1d5e5c.tar.gz lwn-c27c6bd2c4d6b6bb779f9b722d5607993e1d5e5c.zip | |
apparmor: ensure that dfa state tables have entries
Currently it is possible to specify a state machine table with 0 length,
this is not valid as optional tables are specified by not defining
the table as present. Further this allows by-passing the base tables
range check against the next/check tables.
Fixes: d901d6a298dc ("apparmor: dfa split verification of table headers")
Reported-by: Mike Salvatore <mike.salvatore@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security/apparmor')
| -rw-r--r-- | security/apparmor/match.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/security/apparmor/match.c b/security/apparmor/match.c index e605b7d53fb4..3e9e1eaf990e 100644 --- a/security/apparmor/match.c +++ b/security/apparmor/match.c @@ -97,6 +97,9 @@ static struct table_header *unpack_table(char *blob, size_t bsize) th.td_flags == YYTD_DATA8)) goto out; + /* if we have a table it must have some entries */ + if (th.td_lolen == 0) + goto out; tsize = table_size(th.td_lolen, th.td_flags); if (bsize < tsize) goto out; @@ -198,6 +201,8 @@ static int verify_dfa(struct aa_dfa *dfa) state_count = dfa->tables[YYTD_ID_BASE]->td_lolen; trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen; + if (state_count == 0) + goto out; for (i = 0; i < state_count; i++) { if (!(BASE_TABLE(dfa)[i] & MATCH_FLAG_DIFF_ENCODE) && (DEFAULT_TABLE(dfa)[i] >= state_count)) |