On 27-Feb-26 12:37 PM, Marat Khalili wrote:
-----Original Message-----
From: Radu Nicolau <[email protected]>
Sent: Friday 27 February 2026 09:48
To: [email protected]
Cc: Marat Khalili <[email protected]>; Radu Nicolau
<[email protected]>; [email protected];
[email protected]; Yipeng Wang <[email protected]>; Sameh Gobriel
<[email protected]>; Bruce Richardson <[email protected]>;
Vladimir Medvedkin
<[email protected]>; Pablo de Lara <[email protected]>;
Yerden Zhumabekov
<[email protected]>
Subject: [PATCH v2] hash: fix pointer alignment
rte_hash_crc assumes input pointer address is 8 byte aligned
which may not be always the case.
This fix aligns the input pointer before proceeding to process it
in 8 byte chunks.
Fixes: 504a29af13a7 ("hash: fix strict-aliasing for CRC")
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Radu Nicolau <[email protected]>
---
v2: reverse the order of alignment adjustment calls
lib/hash/rte_hash_crc.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/lib/hash/rte_hash_crc.h b/lib/hash/rte_hash_crc.h
index fa07c97685..d61420868a 100644
--- a/lib/hash/rte_hash_crc.h
+++ b/lib/hash/rte_hash_crc.h
@@ -127,6 +127,24 @@ rte_hash_crc(const void *data, uint32_t data_len, uint32_t
init_val)
unsigned i;
uintptr_t pd = (uintptr_t) data;
+ /* align input to 8 byte boundary if needed */
+ if ((pd & 0x7) && data_len >= 8) {
+ uintptr_t unaligned_bytes = 8 - (pd & 0x7);
+ data_len -= unaligned_bytes;
+ if (unaligned_bytes & 0x1) {
+ init_val = rte_hash_crc_1byte(*(const uint8_t *)pd,
init_val);
+ pd += 1;
+ }
+ if (unaligned_bytes & 0x2) {
+ init_val = rte_hash_crc_2byte(*(const uint16_t *)pd,
init_val);
+ pd += 2;
+ }
+ if (unaligned_bytes & 0x4) {
+ init_val = rte_hash_crc_4byte(*(const uint32_t *)pd,
init_val);
+ pd += 4;
+ }
+ }
+
for (i = 0; i < data_len / 8; i++) {
init_val = rte_hash_crc_8byte(*(const uint64_t *)pd, init_val);
pd += 8;
--
2.52.0
Surprisingly, we do not seem to have any tests calling rte_hash_crc with
misaligned data. I tried to tweak existing ones in test_hash.c and
test_hash_functions.c, and found out that rte_hash_crc still fails (with ubsan)
for sizes less than 8 in one of the last 3 if's, and also that jhash has the
same problems. Still this commit is a step in the right direction IMO, so:
Acked-by: Marat Khalili <[email protected]>
Thanks for the ack!
The issue still persist with less that 8 bytes unaligned input because
the 3 ifs after the loop assume the input is aligned, which is the case
only if the loop was taken. I will fix the patch to address this case in
the added section - you were right with the first comment.
