Commit f26a525b authored Sep 09, 2024 by Snehal Koukuntla Committed by Marc Zyngier Sep 10, 2024

KVM: arm64: Add memory length checks and remove inline in do_ffa_mem_xfer



When we share memory through FF-A and the description of the buffers
exceeds the size of the mapped buffer, the fragmentation API is used.
The fragmentation API allows specifying chunks of descriptors in subsequent
FF-A fragment calls and no upper limit has been established for this.
The entire memory region transferred is identified by a handle which can be
used to reclaim the transferred memory.
To be able to reclaim the memory, the description of the buffers has to fit
in the ffa_desc_buf.
Add a bounds check on the FF-A sharing path to prevent the memory reclaim
from failing.

Also do_ffa_mem_xfer() does not need __always_inline, except for the
BUILD_BUG_ON() aspect, which gets moved to a macro.

[maz: fixed the BUILD_BUG_ON() breakage with LLVM, thanks to Wei-Lin Chang
 for the timely report]

Fixes: 634d90cf ("KVM: arm64: Handle FFA_MEM_LEND calls from the host")
Cc: stable@vger.kernel.org
Reviewed-by: Sebastian Ene <sebastianene@google.com>
Signed-off-by: Snehal Koukuntla <snehalreddy@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240909180154.3267939-1-snehalreddy@google.com


Signed-off-by: Marc Zyngier <maz@kernel.org>

parent e0b7de4f

arch/arm64/kvm/hyp/nvhe/ffa.c

+15 −6

Original line number	Diff line number	Diff line
		@@ -426,7 +426,7 @@ static void do_ffa_mem_frag_tx(struct arm_smccc_res *res,
		return;
		}

		static __always_inline void do_ffa_mem_xfer(const u64 func_id,
		static void __do_ffa_mem_xfer(const u64 func_id,
		struct arm_smccc_res *res,
		struct kvm_cpu_context *ctxt)
		{
		@@ -440,9 +440,6 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id,
		u32 offset, nr_ranges;
		int ret = 0;

		BUILD_BUG_ON(func_id != FFA_FN64_MEM_SHARE &&
		func_id != FFA_FN64_MEM_LEND);

		if (addr_mbz \|\| npages_mbz \|\| fraglen > len \|\|
		fraglen > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE) {
		ret = FFA_RET_INVALID_PARAMETERS;
		@@ -461,6 +458,11 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id,
		goto out_unlock;
		}

		if (len > ffa_desc_buf.len) {
		ret = FFA_RET_NO_MEMORY;
		goto out_unlock;
		}

		buf = hyp_buffers.tx;
		memcpy(buf, host_buffers.tx, fraglen);

		@@ -512,6 +514,13 @@ static __always_inline void do_ffa_mem_xfer(const u64 func_id,
		goto out_unlock;
		}

		#define do_ffa_mem_xfer(fid, res, ctxt) \
		do { \
		BUILD_BUG_ON((fid) != FFA_FN64_MEM_SHARE && \
		(fid) != FFA_FN64_MEM_LEND); \
		__do_ffa_mem_xfer((fid), (res), (ctxt)); \
		} while (0);

		static void do_ffa_mem_reclaim(struct arm_smccc_res *res,
		struct kvm_cpu_context *ctxt)
		{