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netfilter: nf_tables: fix pointer math issue in nft_byteorder_eval()

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The problem is in nft_byteorder_eval() where we are iterating through a
loop and writing to dst[0], dst[1], dst[2] and so on...  On each
iteration we are writing 8 bytes.  But dst[] is an array of u32 so each
element only has space for 4 bytes.  That means that every iteration
overwrites part of the previous element.

I spotted this bug while reviewing commit caf3ef7468 ("netfilter:
nf_tables: prevent OOB access in nft_byteorder_eval") which is a related
issue.  I think that the reason we have not detected this bug in testing
is that most of time we only write one element.

Fixes: ce1e7989d9 ("netfilter: nft_byteorder: provide 64bit le/be conversion")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Dan Carpenter 2023-11-03 09:42:51 +03:00 committed by Pablo Neira Ayuso
parent a44af08e3d
commit c301f0981f
3 changed files with 6 additions and 5 deletions
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4
include/net/netfilter/nf_tables.h
View File

@ -178,9 +178,9 @@ static inline __be32 nft_reg_load_be32(const u32 *sreg)
return *(__force __be32 *)sreg;
}
static inline void nft_reg_store64(u32 *dreg, u64 val)
static inline void nft_reg_store64(u64 *dreg, u64 val)
{
put_unaligned(val, (u64 *)dreg);
put_unaligned(val, dreg);
}
static inline u64 nft_reg_load64(const u32 *sreg)

5
net/netfilter/nft_byteorder.c
View File

@ -38,13 +38,14 @@ void nft_byteorder_eval(const struct nft_expr *expr,
switch (priv->size) {
case 8: {
u64 *dst64 = (void *)dst;
u64 src64;
switch (priv->op) {
case NFT_BYTEORDER_NTOH:
for (i = 0; i < priv->len / 8; i++) {
src64 = nft_reg_load64(&src[i]);
nft_reg_store64(&dst[i],
nft_reg_store64(&dst64[i],
be64_to_cpu((__force __be64)src64));
}
break;
@ -52,7 +53,7 @@ void nft_byteorder_eval(const struct nft_expr *expr,
for (i = 0; i < priv->len / 8; i++) {
src64 = (__force __u64)
cpu_to_be64(nft_reg_load64(&src[i]));
nft_reg_store64(&dst[i], src64);
nft_reg_store64(&dst64[i], src64);
}
break;
}

2
net/netfilter/nft_meta.c
View File

@ -63,7 +63,7 @@ nft_meta_get_eval_time(enum nft_meta_keys key,
{
switch (key) {
case NFT_META_TIME_NS:
nft_reg_store64(dest, ktime_get_real_ns());
nft_reg_store64((u64 *)dest, ktime_get_real_ns());
break;
case NFT_META_TIME_DAY:
nft_reg_store8(dest, nft_meta_weekday());