Calls to rte_memcpy_aligned could result in unaligned loads/stores for
1 < n < 16. This is undefined behavior according to the C standard,
and it gets flagged by the clang undefined behavior sanitizer.
rte_memcpy_aligned is called with aligned src and dst addresses. When
n is odd, the code would copy a single byte first, increment src/dst,
then, depending on the value of n, would cast src/dst to a qword, dword
or word pointer. This results in an unaligned load/store. Reversing the
order of the casts & copies (ie. copying a qword first, dword second,
etc.) fixes the issue.
Fixes: d35cc1fe6a7a ("eal/x86: revert select optimized memcpy at run-time")
Cc: Xiaoyun Li <xiaoyun...@intel.com>
Cc: sta...@dpdk.org
Signed-off-by: Luc Pelletier <lucp.at.w...@gmail.com>
---
lib/eal/x86/include/rte_memcpy.h | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/lib/eal/x86/include/rte_memcpy.h b/lib/eal/x86/include/rte_memcpy.h
index 1b6c6e585f..a4eb1316b6 100644
--- a/lib/eal/x86/include/rte_memcpy.h
+++ b/lib/eal/x86/include/rte_memcpy.h
@@ -818,25 +818,25 @@ rte_memcpy_aligned(void *dst, const void *src, size_t n)
{
void *ret = dst;
- /* Copy size <= 16 bytes */
+ /* Copy size < 16 bytes */
if (n < 16) {
- if (n & 0x01) {
- *(uint8_t *)dst = *(const uint8_t *)src;
- src = (const uint8_t *)src + 1;
- dst = (uint8_t *)dst + 1;
- }
- if (n & 0x02) {
- *(uint16_t *)dst = *(const uint16_t *)src;
- src = (const uint16_t *)src + 1;
- dst = (uint16_t *)dst + 1;
+ if (n & 0x08) {
+ *(uint64_t *)dst = *(const uint64_t *)src;
+ src = (const uint64_t *)src + 1;
+ dst = (uint64_t *)dst + 1;
}
if (n & 0x04) {
*(uint32_t *)dst = *(const uint32_t *)src;
src = (const uint32_t *)src + 1;
dst = (uint32_t *)dst + 1;
}
- if (n & 0x08)
- *(uint64_t *)dst = *(const uint64_t *)src;
+ if (n & 0x02) {
+ *(uint16_t *)dst = *(const uint16_t *)src;
+ src = (const uint16_t *)src + 1;
+ dst = (uint16_t *)dst + 1;
+ }
+ if (n & 0x01)
+ *(uint8_t *)dst = *(const uint8_t *)src;
return ret;
}
--
2.25.1
