From: Mostafa Saleh <smostafa@google•com>
To: op-tee@lists•trustedfirmware.org, linux-kernel@vger•kernel.org,
kvmarm@lists•linux.dev, linux-arm-kernel@lists•infradead.org
Cc: maz@kernel•org, oupton@kernel•org, joey.gouly@arm•com,
suzuki.poulose@arm•com, catalin.marinas@arm•com,
jens.wiklander@linaro•org, sumit.garg@kernel•org,
sebastianene@google•com, vdonnefort@google•com,
sudeep.holla@kernel•org, Mostafa Saleh <smostafa@google•com>
Subject: [PATCH v4 3/5] firmware: arm_ffa: Fix Endpoint Memory Access Descriptor offset calculation
Date: Wed, 20 May 2026 20:49:46 +0000 [thread overview]
Message-ID: <20260520204948.2440882-4-smostafa@google.com> (raw)
In-Reply-To: <20260520204948.2440882-1-smostafa@google.com>
From: Sebastian Ene <sebastianene@google•com>
Use the descriptor's `ep_mem_offset` to calculate the start of the endpoint
memory access array and to comply with the FF-A spec instead of defaulting
to `sizeof(struct ffa_mem_region)`.
This requires moving `ffa_mem_region_additional_setup()` earlier in the setup
flow.
Also, add sanity checks to ensure the calculated descriptor offsets do not
exceed `max_fragsize`.
Signed-off-by: Sebastian Ene <sebastianene@google•com>
Signed-off-by: Mostafa Saleh <smostafa@google•com>
---
drivers/firmware/arm_ffa/driver.c | 16 +++++++++++-----
include/linux/arm_ffa.h | 2 +-
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index b700b2e93e72..8573a7a6556e 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -685,19 +685,26 @@ ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize,
struct ffa_composite_mem_region *composite;
struct ffa_mem_region_addr_range *constituents;
struct ffa_mem_region_attributes *ep_mem_access;
- u32 idx, frag_len, length, buf_sz = 0, num_entries = sg_nents(args->sg);
+ u32 idx, frag_len, length, buf_sz = 0, num_entries = sg_nents(args->sg), ep_offset;
+ u32 emad_size = ffa_emad_size_get(drv_info->version);
mem_region->tag = args->tag;
mem_region->flags = args->flags;
mem_region->sender_id = drv_info->vm_id;
mem_region->attributes = ffa_memory_attributes_get(func_id);
+
+ ffa_mem_region_additional_setup(drv_info->version, mem_region);
composite_offset = ffa_mem_desc_offset(buffer, args->nattrs,
drv_info->version);
+ if (composite_offset + sizeof(*composite) > max_fragsize)
+ return -ENXIO;
for (idx = 0; idx < args->nattrs; idx++) {
- ep_mem_access = buffer +
- ffa_mem_desc_offset(buffer, idx, drv_info->version);
- memset(ep_mem_access, 0, ffa_emad_size_get(drv_info->version));
+ ep_offset = ffa_mem_desc_offset(buffer, idx, drv_info->version);
+ if (ep_offset + emad_size > max_fragsize)
+ return -ENXIO;
+ ep_mem_access = buffer + ep_offset;
+ memset(ep_mem_access, 0, emad_size);
ep_mem_access->receiver = args->attrs[idx].receiver;
ep_mem_access->attrs = args->attrs[idx].attrs;
ep_mem_access->composite_off = composite_offset;
@@ -707,7 +714,6 @@ ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize,
}
mem_region->handle = 0;
mem_region->ep_count = args->nattrs;
- ffa_mem_region_additional_setup(drv_info->version, mem_region);
composite = buffer + composite_offset;
composite->total_pg_cnt = ffa_get_num_pages_sg(args->sg);
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index 81e603839c4a..62d67dae8b70 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -445,7 +445,7 @@ ffa_mem_desc_offset(struct ffa_mem_region *buf, int count, u32 ffa_version)
if (!FFA_MEM_REGION_HAS_EP_MEM_OFFSET(ffa_version))
offset += offsetof(struct ffa_mem_region, ep_mem_offset);
else
- offset += sizeof(struct ffa_mem_region);
+ offset += buf->ep_mem_offset;
return offset;
}
--
2.54.0.669.g59709faab0-goog
next prev parent reply other threads:[~2026-05-20 20:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-20 20:49 [PATCH v4 0/5] arm_ffa, KVM: Fix FF-A emad offset calculations Mostafa Saleh
2026-05-20 20:49 ` [PATCH v4 1/5] optee: ffa: Add NULL check in optee_ffa_lend_protmem Mostafa Saleh
2026-05-20 20:49 ` [PATCH v4 2/5] firmware: arm_ffa: Fix out-of-bound writes in ffa_setup_and_transmit() Mostafa Saleh
2026-05-21 12:51 ` Sudeep Holla
2026-05-20 20:49 ` Mostafa Saleh [this message]
2026-05-21 12:55 ` [PATCH v4 3/5] firmware: arm_ffa: Fix Endpoint Memory Access Descriptor offset calculation Sudeep Holla
2026-05-20 20:49 ` [PATCH v4 4/5] KVM: arm64: Fix bounds checking in do_ffa_mem_reclaim() Mostafa Saleh
2026-05-21 8:28 ` Marc Zyngier
2026-05-21 10:30 ` Mostafa Saleh
2026-05-21 10:43 ` Mostafa Saleh
2026-05-21 12:12 ` Marc Zyngier
2026-05-20 20:49 ` [PATCH v4 5/5] KVM: arm64: Validate the offset to the mem access descriptor Mostafa Saleh
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