[PATCH v2 06/11] firmware: arm_ffa: Bound PARTITION_INFO_GET_REGS copies

Sudeep Holla
2026-04-28T18:34:09Z

The register-based PARTITION_INFO_GET path trusted the firmware-provided
indices when copying partition descriptors into the caller buffer.
Reject inconsistent counts or index progressions so the copy loop cannot
write past the allocated array.

Fixes: ba85c644ac8d ("firmware: arm_ffa: Add support for FFA_PARTITION_INFO_GET_REGS")
Signed-off-by: Sudeep Holla <sudeep.holla@kernel.org>
---
drivers/firmware/arm_ffa/driver.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index a122814eb6d7..ed502486eb35 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -323,6 +323,12 @@ __ffa_partition_info_get(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
#define PART_INFO_ID_MASK GENMASK(15, 0)
#define PART_INFO_EXEC_CXT_MASK GENMASK(31, 16)
#define PART_INFO_PROPS_MASK GENMASK(63, 32)
+#define FFA_PART_INFO_GET_REGS_FIRST_REG 3
+#define FFA_PART_INFO_GET_REGS_REGS_PER_DESC 3
+#define FFA_PART_INFO_GET_REGS_MAX_DESC \
+ (((sizeof(ffa_value_t) / sizeof_field(ffa_value_t, a0)) - \
+ FFA_PART_INFO_GET_REGS_FIRST_REG) / \
+ FFA_PART_INFO_GET_REGS_REGS_PER_DESC)
#define PART_INFO_ID(x) ((u16)(FIELD_GET(PART_INFO_ID_MASK, (x))))
#define PART_INFO_EXEC_CXT(x) ((u16)(FIELD_GET(PART_INFO_EXEC_CXT_MASK, (x))))
#define PART_INFO_PROPERTIES(x) ((u32)(FIELD_GET(PART_INFO_PROPS_MASK, (x))))
@@ -336,7 +342,7 @@ __ffa_partition_info_get_regs(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,

do {
__le64 *regs;
- int idx;
+ int idx, nr_desc, buf_idx;

start_idx = prev_idx ? prev_idx + 1 : 0;

@@ -354,15 +360,28 @@ __ffa_partition_info_get_regs(u32 uuid0, u32 uuid1, u32 uuid2, u32 uuid3,
count = PARTITION_COUNT(partition_info.a2);
if (!buffer || !num_parts) /* count only */
return count;
+ if (count > num_parts)
+ return -EINVAL;

cur_idx = CURRENT_INDEX(partition_info.a2);
+ if (cur_idx < start_idx || cur_idx >= count)
+ return -EINVAL;
+
+ nr_desc = cur_idx - start_idx + 1;
+ if (nr_desc > FFA_PART_INFO_GET_REGS_MAX_DESC)
+ return -EINVAL;
+
+ buf_idx = buf - buffer;
+ if (buf_idx + nr_desc > num_parts)
+ return -EINVAL;
+
tag = UUID_INFO_TAG(partition_info.a2);
buf_sz = PARTITION_INFO_SZ(partition_info.a2);
if (buf_sz > sizeof(*buffer))
buf_sz = sizeof(*buffer);

regs = (void *)&partition_info.a3;
- for (idx = 0; idx < cur_idx - start_idx + 1; idx++, buf++) {
+ for (idx = 0; idx < nr_desc; idx++, buf++) {
union {
uuid_t uuid;
u64 regs[2];

--
2.43.0