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| author | Florian Westphal <fw@strlen.de> | 2016-04-01 14:17:27 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-08-22 22:38:30 +0100 |
| commit | 523e5f8924172c7b2f3217e832137076aebc20ee (patch) | |
| tree | 34e774fa84d8cffb7cef0b47532f65280ad8bd93 | |
| parent | 76db4db16a83b74db2bf8136305a73dd23d5cbd0 (diff) | |
| download | lwn-523e5f8924172c7b2f3217e832137076aebc20ee.tar.gz lwn-523e5f8924172c7b2f3217e832137076aebc20ee.zip | |
netfilter: x_tables: check standard target size too
commit 7ed2abddd20cf8f6bd27f65bd218f26fa5bf7f44 upstream.
We have targets and standard targets -- the latter carries a verdict.
The ip/ip6tables validation functions will access t->verdict for the
standard targets to fetch the jump offset or verdict for chainloop
detection, but this happens before the targets get checked/validated.
Thus we also need to check for verdict presence here, else t->verdict
can point right after a blob.
Spotted with UBSAN while testing malformed blobs.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | net/netfilter/x_tables.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c index 90d5aa512293..a504751db670 100644 --- a/net/netfilter/x_tables.c +++ b/net/netfilter/x_tables.c @@ -559,6 +559,13 @@ int xt_compat_match_to_user(const struct xt_entry_match *m, } EXPORT_SYMBOL_GPL(xt_compat_match_to_user); +/* non-compat version may have padding after verdict */ +struct compat_xt_standard_target { + struct compat_xt_entry_target t; + compat_uint_t verdict; +}; + +/* see xt_check_entry_offsets */ int xt_compat_check_entry_offsets(const void *base, unsigned int target_offset, unsigned int next_offset) @@ -576,6 +583,10 @@ int xt_compat_check_entry_offsets(const void *base, if (target_offset + t->u.target_size > next_offset) return -EINVAL; + if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && + target_offset + sizeof(struct compat_xt_standard_target) != next_offset) + return -EINVAL; + return 0; } EXPORT_SYMBOL(xt_compat_check_entry_offsets); @@ -615,6 +626,10 @@ int xt_check_entry_offsets(const void *base, if (target_offset + t->u.target_size > next_offset) return -EINVAL; + if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 && + target_offset + sizeof(struct xt_standard_target) != next_offset) + return -EINVAL; + return 0; } EXPORT_SYMBOL(xt_check_entry_offsets); |