[PATCH 6.1 010/219] powerpc/lib: Validate size for vector operations

Greg Kroah-Hartman
2024-02-03T04:08:37Z

From: Naveen N Rao <naveen@kernel.org>

[ Upstream commit 8f9abaa6d7de0a70fc68acaedce290c1f96e2e59 ]

Some of the fp/vmx code in sstep.c assume a certain maximum size for the
instructions being emulated. The size of those operations however is
determined separately in analyse_instr().

Add a check to validate the assumption on the maximum size of the
operations, so as to prevent any unintended kernel stack corruption.

Signed-off-by: Naveen N Rao <naveen@kernel.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Build-tested-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231123071705.397625-1-naveen@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/lib/sstep.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 398b5694aeb7..ec30af8eadb7 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -586,6 +586,8 @@ static int do_fp_load(struct instruction_op *op, unsigned long ea,
} u;

nb = GETSIZE(op->type);
+ if (nb > sizeof(u))
+ return -EINVAL;
if (!address_ok(regs, ea, nb))
return -EFAULT;
rn = op->reg;
@@ -636,6 +638,8 @@ static int do_fp_store(struct instruction_op *op, unsigned long ea,
} u;

nb = GETSIZE(op->type);
+ if (nb > sizeof(u))
+ return -EINVAL;
if (!address_ok(regs, ea, nb))
return -EFAULT;
rn = op->reg;
@@ -680,6 +684,9 @@ static nokprobe_inline int do_vec_load(int rn, unsigned long ea,
u8 b[sizeof(__vector128)];
} u = {};

+ if (size > sizeof(u))
+ return -EINVAL;
+
if (!address_ok(regs, ea & ~0xfUL, 16))
return -EFAULT;
/* align to multiple of size */
@@ -707,6 +714,9 @@ static nokprobe_inline int do_vec_store(int rn, unsigned long ea,
u8 b[sizeof(__vector128)];
} u;

+ if (size > sizeof(u))
+ return -EINVAL;
+
if (!address_ok(regs, ea & ~0xfUL, 16))
return -EFAULT;
/* align to multiple of size */
--
2.43.0