Included bogon input generates following Sanitizer splat:
AddressSanitizer: dynamic-stack-buffer-overflow on address 0x7...
WRITE of size 2 at 0x7fffffffcbe4 thread T0
#0 0x0000003a68b8 in __asan_memset (src/nft+0x3a68b8) (BuildId: 3678ff51a5405c77e3e0492b9a985910efee73b8)
#1 0x0000004eb603 in __mpz_export_data src/gmputil.c:108:2
#2 0x0000004eb603 in netlink_export_pad src/netlink.c:256:2
#3 0x0000004eb603 in netlink_gen_range src/netlink.c:471:2
#4 0x0000004ea250 in __netlink_gen_data src/netlink.c:523:10
#5 0x0000004e8ee3 in alloc_nftnl_setelem src/netlink.c:205:3
#6 0x0000004d4541 in mnl_nft_setelem_batch src/mnl.c:1816:11
Problem is that the range end is emitted to the buffer at the *padded*
location (rounded up to next register size), but buffer sizing is
based of the expression length, not the padded length.
Also extend the test script: Capture stderr and if we see
AddressSanitizer warning, make it fail.
Same bug as the one fixed in 600b84631410 ("netlink: fix stack buffer overflow with sub-reg sized prefixes"),
just in a different function.
Apply same fix: no dynamic array + add a length check.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
---
src/netlink.c | 11 +++++++----
tests/shell/testcases/bogons/assert_failures | 17 ++++++++++++++++-
...an_stack_buffer_overrun_in_netlink_gen_range | 6 ++++++
3 files changed, 29 insertions(+), 5 deletions(-)
create mode 100644 tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range
diff --git a/src/netlink.c b/src/netlink.c
index 8e6e2066fe2a..52c2d8009b82 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -462,11 +462,14 @@ static void netlink_gen_verdict(const struct expr *expr,
static void netlink_gen_range(const struct expr *expr,
struct nft_data_linearize *nld)
{
- unsigned int len = div_round_up(expr->left->len, BITS_PER_BYTE) * 2;
- unsigned char data[len];
- unsigned int offset = 0;
+ unsigned int len = (netlink_padded_len(expr->left->len) / BITS_PER_BYTE) * 2;
+ unsigned char data[NFT_MAX_EXPR_LEN_BYTES];
+ unsigned int offset;
- memset(data, 0, len);
+ if (len > sizeof(data))
+ BUG("Value export of %u bytes would overflow", len);
+
+ memset(data, 0, sizeof(data));
offset = netlink_export_pad(data, expr->left->value, expr->left);
netlink_export_pad(data + offset, expr->right->value, expr->right);
nft_data_memcpy(nld, data, len);
diff --git a/tests/shell/testcases/bogons/assert_failures b/tests/shell/testcases/bogons/assert_failures
index 79099427c98a..3dee63b3f97b 100755
--- a/tests/shell/testcases/bogons/assert_failures
+++ b/tests/shell/testcases/bogons/assert_failures
@@ -1,12 +1,27 @@
#!/bin/bash
dir=$(dirname $0)/nft-f/
+tmpfile=$(mktemp)
+
+cleanup()
+{
+ rm -f "$tmpfile"
+}
+
+trap cleanup EXIT
for f in $dir/*; do
- $NFT --check -f "$f"
+ echo "Check $f"
+ $NFT --check -f "$f" 2> "$tmpfile"
if [ $? -ne 1 ]; then
echo "Bogus input file $f did not cause expected error code" 1>&2
exit 111
fi
+
+ if grep AddressSanitizer "$tmpfile"; then
+ echo "Address sanitizer splat for $f" 1>&2
+ cat "$tmpfile"
+ exit 111
+ fi
done
diff --git a/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range b/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range
new file mode 100644
index 000000000000..2f7872e4accd
--- /dev/null
+++ b/tests/shell/testcases/bogons/nft-f/asan_stack_buffer_overrun_in_netlink_gen_range
@@ -0,0 +1,6 @@
+table ip test {
+ chain y {
+ redirect to :tcp dport map { 83 : 80/3, 84 :4 }
+ }
+}
+
--
2.45.3
