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| author | Kees Cook <keescook@chromium.org> | 2022-09-21 13:51:55 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2022-09-25 12:52:48 -0400 |
| commit | d88a0240ff76062eb0728963e7aacf6dbe87f7c7 (patch) | |
| tree | 363ed7c30318045053e57b0cbc77e73416fa2b0d | |
| parent | 1a2433b0ec45acd71130bd0bf419394c7d7d85c0 (diff) | |
| download | lwn-d88a0240ff76062eb0728963e7aacf6dbe87f7c7.tar.gz lwn-d88a0240ff76062eb0728963e7aacf6dbe87f7c7.zip | |
scsi: scsi_transport_fc: Adjust struct fc_nl_event flex array usage
In order to help the compiler reason about the destination buffer in struct
fc_nl_event, add a flexible array member for this purpose. However, since
the header is UAPI, it must not change size or layout, so a union is used.
The allocation size calculations are also corrected (it was potentially
allocating an extra 8 bytes), and the padding is zeroed to avoid leaking
kernel heap memory contents.
Detected at run-time by the recently added memcpy() bounds checking:
memcpy: detected field-spanning write (size 8) of single field "&event->event_data" at drivers/scsi/scsi_transport_fc.c:581 (size 4)
Link: https://lore.kernel.org/linux-next/42404B5E-198B-4FD3-94D6-5E16CF579EF3@linux.ibm.com/
Link: https://lore.kernel.org/r/20220921205155.1451649-1-keescook@chromium.org
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Reviewed-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
| -rw-r--r-- | drivers/scsi/scsi_transport_fc.c | 8 | ||||
| -rw-r--r-- | include/uapi/scsi/scsi_netlink_fc.h | 7 |
2 files changed, 10 insertions, 5 deletions
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c index df4aa4a5f83c..8934160c4a33 100644 --- a/drivers/scsi/scsi_transport_fc.c +++ b/drivers/scsi/scsi_transport_fc.c @@ -543,7 +543,7 @@ fc_host_post_fc_event(struct Scsi_Host *shost, u32 event_number, struct nlmsghdr *nlh; struct fc_nl_event *event; const char *name; - u32 len; + size_t len, padding; int err; if (!data_buf || data_len < 4) @@ -554,7 +554,7 @@ fc_host_post_fc_event(struct Scsi_Host *shost, u32 event_number, goto send_fail; } - len = FC_NL_MSGALIGN(sizeof(*event) + data_len); + len = FC_NL_MSGALIGN(sizeof(*event) - sizeof(event->event_data) + data_len); skb = nlmsg_new(len, GFP_KERNEL); if (!skb) { @@ -578,7 +578,9 @@ fc_host_post_fc_event(struct Scsi_Host *shost, u32 event_number, event->event_num = event_number; event->event_code = event_code; if (data_len) - memcpy(&event->event_data, data_buf, data_len); + memcpy(event->event_data_flex, data_buf, data_len); + padding = len - offsetof(typeof(*event), event_data_flex) - data_len; + memset(event->event_data_flex + data_len, 0, padding); nlmsg_multicast(scsi_nl_sock, skb, 0, SCSI_NL_GRP_FC_EVENTS, GFP_KERNEL); diff --git a/include/uapi/scsi/scsi_netlink_fc.h b/include/uapi/scsi/scsi_netlink_fc.h index 7535253f1a96..b46e9cbeb001 100644 --- a/include/uapi/scsi/scsi_netlink_fc.h +++ b/include/uapi/scsi/scsi_netlink_fc.h @@ -35,7 +35,7 @@ * FC Transport Broadcast Event Message : * FC_NL_ASYNC_EVENT * - * Note: if Vendor Unique message, &event_data will be start of + * Note: if Vendor Unique message, event_data_flex will be start of * vendor unique payload, and the length of the payload is * per event_datalen * @@ -50,7 +50,10 @@ struct fc_nl_event { __u16 event_datalen; __u32 event_num; __u32 event_code; - __u32 event_data; + union { + __u32 event_data; + __DECLARE_FLEX_ARRAY(__u8, event_data_flex); + }; } __attribute__((aligned(sizeof(__u64)))); |