[PATCH v2 09/10] stack: fix unaligned accesses on 128-bit

[Bruce Richardson]

On Mon, Jun 23, 2025 at 03:52:39PM +0200, David Marchand wrote:
> Caught by UBSan:
> 
> ../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
> 	member access within misaligned address 0x7ffd9c67f228 for
> 	type 'const rte_int128_t', which requires 16 byte alignment
> 	0x7ffd9c67f228: note: pointer points here
>  00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
>               ^
>  00 00 00 00 00 00 00 00  00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> 	../lib/eal/x86/include/rte_atomic_64.h:206:21 in
> 	../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
> 	member access within misaligned address 0x7ffd9c67f228 for type
> 	'const union rte_int128_t::(anonymous at
> 	../lib/eal/include/generic/rte_atomic.h:1102:2)', which requires
> 	16 byte alignment
> 0x7ffd9c67f228: note: pointer points here
>  00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
>               ^
>  00 00 00 00 00 00 00 00  00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> 	../lib/eal/x86/include/rte_atomic_64.h:206:21 in
> 	../lib/eal/x86/include/rte_atomic_64.h:206:16: runtime error:
> 	load of misaligned address 0x7ffd9c67f228 for type
> 	'const uint64_t' (aka 'const unsigned long'), which requires
> 	16 byte alignment
> 0x7ffd9c67f228: note: pointer points here
>  00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
>               ^
>  00 00 00 00 00 00 00 00  00 00 00 00
> SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
> 	../lib/eal/x86/include/rte_atomic_64.h:206:21 in
> 
> Fixes: 3340202f5954 ("stack: add lock-free implementation")
> Cc: stable at dpdk.org
> 
> Signed-off-by: David Marchand <david.marchand at redhat.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>