diff options
| author | Florian Westphal <fw@strlen.de> | 2026-06-09 21:28:09 +0200 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2026-06-10 18:00:12 +0200 |
| commit | 772cecf198da732faebb5dcfc46d66a505be8495 (patch) | |
| tree | 477ccc145bc5973aa7d806445cd8e4f6b38a0b4c | |
| parent | a84b6fedbc97078788be78dbdd7517d143ad1a77 (diff) | |
netfilter: nft_exthdr: fix register tracking for F_PRESENT flag
nft_exthdr_init() passes user-controlled priv->len to
nft_parse_register_store(), which marks that many bytes in the
register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT
is set, the eval paths write only 1 byte (nft_reg_store8) or
4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4,
registers beyond the first are never written, retaining
uninitialized stack data from nft_regs.
Bail out if userspace requests too much data when F_PRESENT is set.
Reported-by: Ji'an Zhou <eilaimemedsnaimel@gmail.com>
Fixes: c078ca3b0c5b ("netfilter: nft_exthdr: Add support for existence check")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nft_exthdr.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index e6a07c0df207..d3fc7969f123 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -532,6 +532,9 @@ static int nft_exthdr_init(const struct nft_ctx *ctx, return err; } + if ((flags & NFT_EXTHDR_F_PRESENT) && len != 1) + return -EINVAL; + priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]); priv->offset = offset; priv->len = len; |