From: Johannes Berg <johannes.berg@xxxxxxxxx>
If we just want to determine the length of the fragmented
data, we basically need the same logic, and really we want
it to be _literally_ the same logic, so it cannot be out
of sync in any way.
Allow calling cfg80211_defragment_element() without an output
buffer, where it then just returns the required output size.
Also add this to the tests, just to exercise it, using the
pre-calculated length to really do the defragmentation, which
checks that this is sufficient.
Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@xxxxxxxxx>
Reviewed-by: Benjamin Berg <benjamin.berg@xxxxxxxxx>
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/net/cfg80211.h | 4 ++--
net/wireless/scan.c | 27 ++++++++++++++++++---------
net/wireless/tests/fragmentation.c | 30 +++++++++++++++++++++++++-----
3 files changed, 45 insertions(+), 16 deletions(-)
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 53653d234d39..2e2be4fd2bb6 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -6908,8 +6908,8 @@ bool cfg80211_iter_rnr(const u8 *elems, size_t elems_len,
* @elem: the element to defragment
* @ies: elements where @elem is contained
* @ieslen: length of @ies
- * @data: buffer to store element data
- * @data_len: length of @data
+ * @data: buffer to store element data, or %NULL to just determine size
+ * @data_len: length of @data, or 0
* @frag_id: the element ID of fragments
*
* Return: length of @data, or -EINVAL on error
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 9377a43aa5f7..5a5dd3ce497f 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2504,16 +2504,22 @@ ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
if (elem->id == WLAN_EID_EXTENSION) {
copied = elem->datalen - 1;
- if (copied > data_len)
- return -ENOSPC;
- memmove(data, elem->data + 1, copied);
+ if (data) {
+ if (copied > data_len)
+ return -ENOSPC;
+
+ memmove(data, elem->data + 1, copied);
+ }
} else {
copied = elem->datalen;
- if (copied > data_len)
- return -ENOSPC;
- memmove(data, elem->data, copied);
+ if (data) {
+ if (copied > data_len)
+ return -ENOSPC;
+
+ memmove(data, elem->data, copied);
+ }
}
/* Fragmented elements must have 255 bytes */
@@ -2532,10 +2538,13 @@ ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
elem_datalen = elem->datalen;
- if (copied + elem_datalen > data_len)
- return -ENOSPC;
+ if (data) {
+ if (copied + elem_datalen > data_len)
+ return -ENOSPC;
+
+ memmove(data + copied, elem->data, elem_datalen);
+ }
- memmove(data + copied, elem->data, elem_datalen);
copied += elem_datalen;
/* Only the last fragment may be short */
diff --git a/net/wireless/tests/fragmentation.c b/net/wireless/tests/fragmentation.c
index 49a339ca8880..411fae18cd88 100644
--- a/net/wireless/tests/fragmentation.c
+++ b/net/wireless/tests/fragmentation.c
@@ -2,7 +2,7 @@
/*
* KUnit tests for element fragmentation
*
- * Copyright (C) 2023 Intel Corporation
+ * Copyright (C) 2023-2024 Intel Corporation
*/
#include <linux/ieee80211.h>
#include <net/cfg80211.h>
@@ -27,7 +27,12 @@ static void defragment_0(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
- data, sizeof(input),
+ NULL, 0,
+ WLAN_EID_FRAGMENT);
+ KUNIT_EXPECT_EQ(test, ret, 253);
+ ret = cfg80211_defragment_element((void *)input,
+ input, sizeof(input),
+ data, ret,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 253);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 253);
@@ -63,7 +68,12 @@ static void defragment_1(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
- data, sizeof(input),
+ NULL, 0,
+ WLAN_EID_FRAGMENT);
+ KUNIT_EXPECT_EQ(test, ret, 254 + 7);
+ ret = cfg80211_defragment_element((void *)input,
+ input, sizeof(input),
+ data, ret,
WLAN_EID_FRAGMENT);
/* this means the last fragment was not used */
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
@@ -106,10 +116,15 @@ static void defragment_2(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
- data, sizeof(input),
+ NULL, 0,
WLAN_EID_FRAGMENT);
/* this means the last fragment was not used */
KUNIT_EXPECT_EQ(test, ret, 254 + 255 + 1);
+ ret = cfg80211_defragment_element((void *)input,
+ input, sizeof(input),
+ data, ret,
+ WLAN_EID_FRAGMENT);
+ KUNIT_EXPECT_EQ(test, ret, 254 + 255 + 1);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 254);
KUNIT_EXPECT_MEMEQ(test, data + 254, input + 257 + 2, 255);
KUNIT_EXPECT_MEMEQ(test, data + 254 + 255, input + 2 * 257 + 2, 1);
@@ -134,7 +149,12 @@ static void defragment_at_end(struct kunit *test)
ret = cfg80211_defragment_element((void *)input,
input, sizeof(input),
- data, sizeof(input),
+ NULL, 0,
+ WLAN_EID_FRAGMENT);
+ KUNIT_EXPECT_EQ(test, ret, 254 + 7);
+ ret = cfg80211_defragment_element((void *)input,
+ input, sizeof(input),
+ data, ret,
WLAN_EID_FRAGMENT);
KUNIT_EXPECT_EQ(test, ret, 254 + 7);
KUNIT_EXPECT_MEMEQ(test, data, input + 3, 254);
--
2.43.2
