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s390/zcrypt: fix warning about field-spanning write

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This patch fixes the warning

memcpy: detected field-spanning write (size 60) of single field "to" at drivers/s390/crypto/zcrypt_api.h:173 (size 2)
WARNING: CPU: 1 PID: 2114 at drivers/s390/crypto/zcrypt_api.h:173 prep_ep11_ap_msg+0x2c6/0x2e0 [zcrypt]

The code has been rewritten to use a union in combination
with a flex array to clearly state which part of the buffer
the payload is to be copied in via z_copy_from_user
function (which may call memcpy() in case of in-kernel calls).

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Suggested-by: Jürgen Christ <jchrist@linux.ibm.com>
Reviewed-by: Jürgen Christ <jchrist@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Harald Freudenberger 2022-10-25 10:05:25 +02:00 committed by Vasily Gorbik
parent e38de48044
commit b43088f30d
1 changed files with 15 additions and 6 deletions
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15
drivers/s390/crypto/zcrypt_msgtype6.c
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@ -342,7 +342,10 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg,
};
struct {
struct type6_hdr hdr;
union {
struct CPRBX cprbx;
DECLARE_FLEX_ARRAY(u8, userdata);
};
} __packed * msg = ap_msg->msg;
int rcblen = CEIL4(xcrb->request_control_blk_length);
@ -403,7 +406,8 @@ static int xcrb_msg_to_type6cprb_msgx(bool userspace, struct ap_message *ap_msg,
msg->hdr.fromcardlen2 = xcrb->reply_data_length;
/* prepare CPRB */
if (z_copy_from_user(userspace, &msg->cprbx, xcrb->request_control_blk_addr,
if (z_copy_from_user(userspace, msg->userdata,
xcrb->request_control_blk_addr,
xcrb->request_control_blk_length))
return -EFAULT;
if (msg->cprbx.cprb_len + sizeof(msg->hdr.function_code) >
@ -469,9 +473,14 @@ static int xcrb_msg_to_type6_ep11cprb_msgx(bool userspace, struct ap_message *ap
struct {
struct type6_hdr hdr;
union {
struct {
struct ep11_cprb cprbx;
unsigned char pld_tag; /* fixed value 0x30 */
unsigned char pld_lenfmt; /* payload length format */
unsigned char pld_lenfmt; /* length format */
} __packed;
DECLARE_FLEX_ARRAY(u8, userdata);
};
} __packed * msg = ap_msg->msg;
struct pld_hdr {
@ -500,7 +509,7 @@ static int xcrb_msg_to_type6_ep11cprb_msgx(bool userspace, struct ap_message *ap
msg->hdr.fromcardlen1 = xcrb->resp_len;
/* Import CPRB data from the ioctl input parameter */
if (z_copy_from_user(userspace, &msg->cprbx.cprb_len,
if (z_copy_from_user(userspace, msg->userdata,
(char __force __user *)xcrb->req, xcrb->req_len)) {
return -EFAULT;
}