From 0857515c943d439eade80710c16f15f146dfa9e8 Mon Sep 17 00:00:00 2001
From: David Gibson <david@gibson.dropbear.id.au>
Date: Mon, 17 Mar 2025 20:24:23 +1100
Subject: [PATCH] packet: ASSERT on signs of pool corruption
If packet_check_range() fails in packet_get_try_do() we just return NULL.
But this check only takes places after we've already validated the given
range against the packet it's in. That means that if packet_check_range()
fails, the packet pool is already in a corrupted state (we should have
made strictly stronger checks when the packet was added). Simply returning
NULL and logging a trace() level message isn't really adequate for that
situation; ASSERT instead.
Similarly we check the given idx against both p->count and p->size. The
latter should be redundant, because count should always be <= size. If
that's not the case then, again, the pool is already in a corrupted state
and we may have overwritten unknown memory. Assert for this case too.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
packet.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/packet.c b/packet.c
index b3e8c79..be28f27 100644
--- a/packet.c
+++ b/packet.c
@@ -129,9 +129,13 @@ void *packet_get_try_do(const struct pool *p, size_t idx, size_t offset,
{
char *ptr;
- if (idx >= p->size || idx >= p->count) {
- trace("packet %zu from pool size: %zu, count: %zu, %s:%i",
- idx, p->size, p->count, func, line);
+ ASSERT_WITH_MSG(p->count <= p->size,
+ "Corrupt pool count: %zu, size: %zu, %s:%i",
+ p->count, p->size, func, line);
+
+ if (idx >= p->count) {
+ trace("packet %zu from pool count: %zu, %s:%i",
+ idx, p->count, func, line);
return NULL;
}
@@ -141,8 +145,8 @@ void *packet_get_try_do(const struct pool *p, size_t idx, size_t offset,
ptr = (char *)p->pkt[idx].iov_base + offset;
- if (packet_check_range(p, ptr, len, func, line))
- return NULL;
+ ASSERT_WITH_MSG(!packet_check_range(p, ptr, len, func, line),
+ "Corrupt packet pool, %s:%i", func, line);
if (left)
*left = p->pkt[idx].iov_len - offset - len;