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authorWander Lairson Costa <wander@redhat.com>2023-09-01 10:50:20 -0300
committerFlorian Westphal <fw@strlen.de>2023-09-06 18:07:49 +0200
commitf4f8a7803119005e87b716874bec07c751efafec (patch)
tree88445d6614367be497253ac34d32c33c21ec3f32 /net
parentfd94d9dadee58e09b49075240fe83423eb1dcd36 (diff)
netfilter: nfnetlink_osf: avoid OOB read
The opt_num field is controlled by user mode and is not currently validated inside the kernel. An attacker can take advantage of this to trigger an OOB read and potentially leak information. BUG: KASAN: slab-out-of-bounds in nf_osf_match_one+0xbed/0xd10 net/netfilter/nfnetlink_osf.c:88 Read of size 2 at addr ffff88804bc64272 by task poc/6431 CPU: 1 PID: 6431 Comm: poc Not tainted 6.0.0-rc4 #1 Call Trace: nf_osf_match_one+0xbed/0xd10 net/netfilter/nfnetlink_osf.c:88 nf_osf_find+0x186/0x2f0 net/netfilter/nfnetlink_osf.c:281 nft_osf_eval+0x37f/0x590 net/netfilter/nft_osf.c:47 expr_call_ops_eval net/netfilter/nf_tables_core.c:214 nft_do_chain+0x2b0/0x1490 net/netfilter/nf_tables_core.c:264 nft_do_chain_ipv4+0x17c/0x1f0 net/netfilter/nft_chain_filter.c:23 [..] Also add validation to genre, subtype and version fields. Fixes: 11eeef41d5f6 ("netfilter: passive OS fingerprint xtables match") Reported-by: Lucas Leong <wmliang@infosec.exchange> Signed-off-by: Wander Lairson Costa <wander@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nfnetlink_osf.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index 8f1bfa6ccc2d..50723ba08289 100644
--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -315,6 +315,14 @@ static int nfnl_osf_add_callback(struct sk_buff *skb,
f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
+ if (f->opt_num > ARRAY_SIZE(f->opt))
+ return -EINVAL;
+
+ if (!memchr(f->genre, 0, MAXGENRELEN) ||
+ !memchr(f->subtype, 0, MAXGENRELEN) ||
+ !memchr(f->version, 0, MAXGENRELEN))
+ return -EINVAL;
+
kf = kmalloc(sizeof(struct nf_osf_finger), GFP_KERNEL);
if (!kf)
return -ENOMEM;