[PATCH v2] tools: usb: ffs-test: read the descriptor counts with unaligned accesses

[Sasha Levin <sashal@kernel.org>]

descs_to_legacy() reads the descriptor counts through a __le32 pointer
taken from a member of a packed struct, which may be unaligned:

  ffs-test.c:235:40: warning: taking address of packed member of 'struct <anonymous>' may result in an unaligned pointer value [-Waddress-of-packed-member]

Walk the counts with a byte pointer and get_unaligned_le32().

Fixes: b9a4274699c69 ("tools: ffs-test: add compatibility code for old kernels")
Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
Changes in v2:
- Take the byte pointer from in->counts instead of computing it from
  descriptors_v2 (Michał Nazarewicz)
- Link to v1: https://lore.kernel.org/r/20261011223445.2328181-1-sashal@kernel.org

 tools/usb/ffs-test.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/usb/ffs-test.c b/tools/usb/ffs-test.c
index 22b938fbdfb77..4453d810e9412 100644
--- a/tools/usb/ffs-test.c
+++ b/tools/usb/ffs-test.c
@@ -232,7 +232,7 @@ static size_t descs_to_legacy(void **legacy, const void *descriptors_v2)
 			const struct usb_functionfs_descs_head_v2 header;
 			const __le32 counts[];
 		} __attribute__((packed)) *const in = descriptors_v2;
-		const __le32 *counts = in->counts;
+		const unsigned char *counts = (const void *)in->counts;
 		__u32 flags;
 
 		if (le32_to_cpu(in->header.magic) !=
@@ -252,9 +252,9 @@ static size_t descs_to_legacy(void **legacy, const void *descriptors_v2)
 				break;			\
 			if (length < 4)			\
 				return 0;		\
-			ret = le32_to_cpu(*counts);	\
+			ret = get_unaligned_le32(counts); \
 			length -= 4;			\
-			++counts;			\
+			counts += 4;			\
 		} while (0)
 
 		GET_NEXT_COUNT_IF_FLAG(fs_count, FUNCTIONFS_HAS_FS_DESC);
-- 
2.53.0