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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