From 1da41666acfe3c91c75563f4694b41e2ea52138e Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Mon, 28 Apr 2025 15:06:43 +0200 Subject: [PATCH] tee: Prevent size calculation wraparound on 32-bit kernels [ Upstream commit 39bb67edcc582b3b386a9ec983da67fa8a10ec03 ] The current code around TEE_IOCTL_PARAM_SIZE() is a bit wrong on 32-bit kernels: Multiplying a user-provided 32-bit value with the size of a structure can wrap around on such platforms. Fix it by using saturating arithmetic for the size calculation. This has no security consequences because, in all users of TEE_IOCTL_PARAM_SIZE(), the subsequent kcalloc() implicitly checks for wrapping. Signed-off-by: Jann Horn Signed-off-by: Jens Wiklander Tested-by: Rouven Czerwinski Signed-off-by: Sasha Levin Signed-off-by: Ulrich Hecht --- drivers/tee/tee_core.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c index a548c3695797..1009c691d913 100644 --- a/drivers/tee/tee_core.c +++ b/drivers/tee/tee_core.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -26,7 +27,7 @@ #define TEE_NUM_DEVICES 32 -#define TEE_IOCTL_PARAM_SIZE(x) (sizeof(struct tee_param) * (x)) +#define TEE_IOCTL_PARAM_SIZE(x) (size_mul(sizeof(struct tee_param), (x))) /* * Unprivileged devices in the lower half range and privileged devices in @@ -270,7 +271,7 @@ static int tee_ioctl_open_session(struct tee_context *ctx, if (copy_from_user(&arg, uarg, sizeof(arg))) return -EFAULT; - if (sizeof(arg) + TEE_IOCTL_PARAM_SIZE(arg.num_params) != buf.buf_len) + if (size_add(sizeof(arg), TEE_IOCTL_PARAM_SIZE(arg.num_params)) != buf.buf_len) return -EINVAL; if (arg.num_params) { @@ -341,7 +342,7 @@ static int tee_ioctl_invoke(struct tee_context *ctx, if (copy_from_user(&arg, uarg, sizeof(arg))) return -EFAULT; - if (sizeof(arg) + TEE_IOCTL_PARAM_SIZE(arg.num_params) != buf.buf_len) + if (size_add(sizeof(arg), TEE_IOCTL_PARAM_SIZE(arg.num_params)) != buf.buf_len) return -EINVAL; if (arg.num_params) { @@ -475,7 +476,7 @@ static int tee_ioctl_supp_recv(struct tee_context *ctx, if (get_user(num_params, &uarg->num_params)) return -EFAULT; - if (sizeof(*uarg) + TEE_IOCTL_PARAM_SIZE(num_params) != buf.buf_len) + if (size_add(sizeof(*uarg), TEE_IOCTL_PARAM_SIZE(num_params)) != buf.buf_len) return -EINVAL; params = kcalloc(num_params, sizeof(struct tee_param), GFP_KERNEL); @@ -570,7 +571,7 @@ static int tee_ioctl_supp_send(struct tee_context *ctx, get_user(num_params, &uarg->num_params)) return -EFAULT; - if (sizeof(*uarg) + TEE_IOCTL_PARAM_SIZE(num_params) > buf.buf_len) + if (size_add(sizeof(*uarg), TEE_IOCTL_PARAM_SIZE(num_params)) > buf.buf_len) return -EINVAL; params = kcalloc(num_params, sizeof(struct tee_param), GFP_KERNEL);