From: Andy Lutomirski Date: Wed, 28 May 2014 23:09:58 -0400 Subject: auditsc: audit_krule mask accesses need bounds checking Origin: https://git.kernel.org/linus/a3c54931199565930d6d84f4c3456f6440aefd41 Fixes an easy DoS and possible information disclosure. This does nothing about the broken state of x32 auditing. eparis: If the admin has enabled auditd and has specifically loaded audit rules. This bug has been around since before git. Wow... Cc: stable@vger.kernel.org Signed-off-by: Andy Lutomirski Signed-off-by: Eric Paris Signed-off-by: Linus Torvalds --- kernel/auditsc.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -720,6 +720,22 @@ static enum audit_state audit_filter_tas return AUDIT_BUILD_CONTEXT; } +static int audit_in_mask(const struct audit_krule *rule, unsigned long val) +{ + int word, bit; + + if (val > 0xffffffff) + return false; + + word = AUDIT_WORD(val); + if (word >= AUDIT_BITMASK_SIZE) + return false; + + bit = AUDIT_BIT(val); + + return rule->mask[word] & bit; +} + /* At syscall entry and exit time, this filter is called if the * audit_state is not low enough that auditing cannot take place, but is * also not high enough that we already know we have to write an audit @@ -737,11 +753,8 @@ static enum audit_state audit_filter_sys rcu_read_lock(); if (!list_empty(list)) { - int word = AUDIT_WORD(ctx->major); - int bit = AUDIT_BIT(ctx->major); - list_for_each_entry_rcu(e, list, list) { - if ((e->rule.mask[word] & bit) == bit && + if (audit_in_mask(&e->rule, ctx->major) && audit_filter_rules(tsk, &e->rule, ctx, NULL, &state, false)) { rcu_read_unlock(); @@ -761,20 +774,16 @@ static enum audit_state audit_filter_sys static int audit_filter_inode_name(struct task_struct *tsk, struct audit_names *n, struct audit_context *ctx) { - int word, bit; int h = audit_hash_ino((u32)n->ino); struct list_head *list = &audit_inode_hash[h]; struct audit_entry *e; enum audit_state state; - word = AUDIT_WORD(ctx->major); - bit = AUDIT_BIT(ctx->major); - if (list_empty(list)) return 0; list_for_each_entry_rcu(e, list, list) { - if ((e->rule.mask[word] & bit) == bit && + if (audit_in_mask(&e->rule, ctx->major) && audit_filter_rules(tsk, &e->rule, ctx, n, &state, false)) { ctx->current_state = state; return 1;