wl3501_cs: Fix out-of-bounds warnings in wl3501_mgmt_join

Fix the following out-of-bounds warnings by adding a new structure
wl3501_req instead of duplicating the same members in structure
wl3501_join_req and wl3501_scan_confirm:

arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [39, 108] from the object at 'sig' is out of the bounds of referenced subobject 'beacon_period' with type 'short unsigned int' at offset 36 [-Warray-bounds]
arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [25, 95] from the object at 'sig' is out of the bounds of referenced subobject 'beacon_period' with type 'short unsigned int' at offset 22 [-Warray-bounds]

Refactor the code, accordingly:

$ pahole -C wl3501_req drivers/net/wireless/wl3501_cs.o
struct wl3501_req {
        u16                        beacon_period;        /*     0     2 */
        u16                        dtim_period;          /*     2     2 */
        u16                        cap_info;             /*     4     2 */
        u8                         bss_type;             /*     6     1 */
        u8                         bssid[6];             /*     7     6 */
        struct iw_mgmt_essid_pset  ssid;                 /*    13    34 */
        struct iw_mgmt_ds_pset     ds_pset;              /*    47     3 */
        struct iw_mgmt_cf_pset     cf_pset;              /*    50     8 */
        struct iw_mgmt_ibss_pset   ibss_pset;            /*    58     4 */
        struct iw_mgmt_data_rset   bss_basic_rset;       /*    62    10 */

        /* size: 72, cachelines: 2, members: 10 */
        /* last cacheline: 8 bytes */
};

$ pahole -C wl3501_join_req drivers/net/wireless/wl3501_cs.o
struct wl3501_join_req {
        u16                        next_blk;             /*     0     2 */
        u8                         sig_id;               /*     2     1 */
        u8                         reserved;             /*     3     1 */
        struct iw_mgmt_data_rset   operational_rset;     /*     4    10 */
        u16                        reserved2;            /*    14     2 */
        u16                        timeout;              /*    16     2 */
        u16                        probe_delay;          /*    18     2 */
        u8                         timestamp[8];         /*    20     8 */
        u8                         local_time[8];        /*    28     8 */
        struct wl3501_req          req;                  /*    36    72 */

        /* size: 108, cachelines: 2, members: 10 */
        /* last cacheline: 44 bytes */
};

$ pahole -C wl3501_scan_confirm drivers/net/wireless/wl3501_cs.o
struct wl3501_scan_confirm {
        u16                        next_blk;             /*     0     2 */
        u8                         sig_id;               /*     2     1 */
        u8                         reserved;             /*     3     1 */
        u16                        status;               /*     4     2 */
        char                       timestamp[8];         /*     6     8 */
        char                       localtime[8];         /*    14     8 */
        struct wl3501_req          req;                  /*    22    72 */
        /* --- cacheline 1 boundary (64 bytes) was 30 bytes ago --- */
        u8                         rssi;                 /*    94     1 */

        /* size: 96, cachelines: 2, members: 8 */
        /* padding: 1 */
        /* last cacheline: 32 bytes */
};

The problem is that the original code is trying to copy data into a
bunch of struct members adjacent to each other in a single call to
memcpy(). Now that a new struct wl3501_req enclosing all those adjacent
members is introduced, memcpy() doesn't overrun the length of
&sig.beacon_period and &this->bss_set[i].beacon_period, because the
address of the new struct object _req_ is used as the destination,
instead.

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1fbaf516da763b50edac47d792a9145aa4482e29.1618442265.git.gustavoars@kernel.org

1 files changed, 15 insertions, 20 deletions

diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h
index 8c5480bec104..91f276dd22a1 100644
--- a/drivers/net/wireless/wl3501.h
+++ b/drivers/net/wireless/wl3501.h
@@ -379,16 +379,7 @@ struct wl3501_get_confirm {
 	u8	mib_value[100];
 };
 
-struct wl3501_join_req {
-	u16			    next_blk;
-	u8			    sig_id;
-	u8			    reserved;
-	struct iw_mgmt_data_rset    operational_rset;
-	u16			    reserved2;
-	u16			    timeout;
-	u16			    probe_delay;
-	u8			    timestamp[8];
-	u8			    local_time[8];
+struct wl3501_req {
 	u16			    beacon_period;
 	u16			    dtim_period;
 	u16			    cap_info;
@@ -401,6 +392,19 @@ struct wl3501_join_req {
 	struct iw_mgmt_data_rset    bss_basic_rset;
 };
 
+struct wl3501_join_req {
+	u16			    next_blk;
+	u8			    sig_id;
+	u8			    reserved;
+	struct iw_mgmt_data_rset    operational_rset;
+	u16			    reserved2;
+	u16			    timeout;
+	u16			    probe_delay;
+	u8			    timestamp[8];
+	u8			    local_time[8];
+	struct wl3501_req	    req;
+};
+
 struct wl3501_join_confirm {
 	u16	next_blk;
 	u8	sig_id;
@@ -443,16 +447,7 @@ struct wl3501_scan_confirm {
 	u16			    status;
 	char			    timestamp[8];
 	char			    localtime[8];
-	u16			    beacon_period;
-	u16			    dtim_period;
-	u16			    cap_info;
-	u8			    bss_type;
-	u8			    bssid[ETH_ALEN];
-	struct iw_mgmt_essid_pset   ssid;
-	struct iw_mgmt_ds_pset	    ds_pset;
-	struct iw_mgmt_cf_pset	    cf_pset;
-	struct iw_mgmt_ibss_pset    ibss_pset;
-	struct iw_mgmt_data_rset    bss_basic_rset;
+	struct wl3501_req	    req;
 	u8			    rssi;
 };