From 7d7d7e02111e9a4dc9d0658597f528f815d820fd Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 27 Feb 2018 19:42:35 +0100 Subject: [PATCH] netfilter: compat: reject huge allocation requests no need to bother even trying to allocating huge compat offset arrays, such ruleset is rejected later on anyway becaus we refuse to allocate overly large rule blobs. However, compat translation happens before blob allocation, so we should add a check there too. This is supposed to help with fuzzing by avoiding oom-killer. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/x_tables.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index e878c85a9268..33724b08b8f0 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -582,14 +582,8 @@ int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta) { struct xt_af *xp = &xt[af]; - if (!xp->compat_tab) { - if (!xp->number) - return -EINVAL; - xp->compat_tab = vmalloc(sizeof(struct compat_delta) * xp->number); - if (!xp->compat_tab) - return -ENOMEM; - xp->cur = 0; - } + if (WARN_ON(!xp->compat_tab)) + return -ENOMEM; if (xp->cur >= xp->number) return -EINVAL; @@ -634,6 +628,22 @@ EXPORT_SYMBOL_GPL(xt_compat_calc_jump); int xt_compat_init_offsets(u8 af, unsigned int number) { + size_t mem; + + if (!number || number > (INT_MAX / sizeof(struct compat_delta))) + return -EINVAL; + + if (WARN_ON(xt[af].compat_tab)) + return -EINVAL; + + mem = sizeof(struct compat_delta) * number; + if (mem > XT_MAX_TABLE_SIZE) + return -ENOMEM; + + xt[af].compat_tab = vmalloc(mem); + if (!xt[af].compat_tab) + return -ENOMEM; + xt[af].number = number; xt[af].cur = 0; -- 2.11.0