by Sasha Levin

[permalink] [raw]

Subject: [PATCH AUTOSEL 5.12 100/116] wl3501_cs: Fix out-of-bounds warnings in wl3501_send_pkt

From: "Gustavo A. R. Silva" <[email protected]>

[ Upstream commit 820aa37638a252b57967bdf4038a514b1ab85d45 ]

Fix the following out-of-bounds warnings by enclosing structure members
daddr and saddr into new struct addr, in structures wl3501_md_req and
wl3501_md_ind:

arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [18, 23] from the object at 'sig' is out of the bounds of referenced subobject 'daddr' with type 'u8[6]' {aka 'unsigned char[6]'} at offset 11 [-Warray-bounds]
arch/x86/include/asm/string_32.h:182:25: warning: '__builtin_memcpy' offset [18, 23] from the object at 'sig' is out of the bounds of referenced subobject 'daddr' with type 'u8[6]' {aka 'unsigned char[6]'} at offset 11 [-Warray-bounds]

Refactor the code, accordingly:

$ pahole -C wl3501_md_req drivers/net/wireless/wl3501_cs.o
struct wl3501_md_req {
u16 next_blk; /* 0 2 */
u8 sig_id; /* 2 1 */
u8 routing; /* 3 1 */
u16 data; /* 4 2 */
u16 size; /* 6 2 */
u8 pri; /* 8 1 */
u8 service_class; /* 9 1 */
struct {
u8 daddr[6]; /* 10 6 */
u8 saddr[6]; /* 16 6 */
} addr; /* 10 12 */

/* size: 22, cachelines: 1, members: 8 */
/* last cacheline: 22 bytes */
};

$ pahole -C wl3501_md_ind drivers/net/wireless/wl3501_cs.o
struct wl3501_md_ind {
u16 next_blk; /* 0 2 */
u8 sig_id; /* 2 1 */
u8 routing; /* 3 1 */
u16 data; /* 4 2 */
u16 size; /* 6 2 */
u8 reception; /* 8 1 */
u8 pri; /* 9 1 */
u8 service_class; /* 10 1 */
struct {
u8 daddr[6]; /* 11 6 */
u8 saddr[6]; /* 17 6 */
} addr; /* 11 12 */

/* size: 24, cachelines: 1, members: 9 */
/* padding: 1 */
/* last cacheline: 24 bytes */
};

The problem is that the original code is trying to copy data into a
couple of arrays adjacent to each other in a single call to memcpy().
Now that a new struct _addr_ enclosing those two adjacent arrays
is introduced, memcpy() doesn't overrun the length of &sig.daddr[0]
and &sig.daddr, because the address of the new struct object _addr_
is used, 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 <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Gustavo A. R. Silva <[email protected]>
Signed-off-by: Kalle Valo <[email protected]>
Link: https://lore.kernel.org/r/d260fe56aed7112bff2be5b4d152d03ad7b78e78.1618442265.git.gustavoars@kernel.org
Signed-off-by: Sasha Levin <[email protected]>
---
drivers/net/wireless/wl3501.h | 12 ++++++++----
drivers/net/wireless/wl3501_cs.c | 10 ++++++----
2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h
index e98e04ee9a2c..aa8222cbea68 100644
--- a/drivers/net/wireless/wl3501.h
+++ b/drivers/net/wireless/wl3501.h
@@ -471,8 +471,10 @@ struct wl3501_md_req {
u16 size;
u8 pri;
u8 service_class;
- u8 daddr[ETH_ALEN];
- u8 saddr[ETH_ALEN];
+ struct {
+ u8 daddr[ETH_ALEN];
+ u8 saddr[ETH_ALEN];
+ } addr;
};

struct wl3501_md_ind {
@@ -484,8 +486,10 @@ struct wl3501_md_ind {
u8 reception;
u8 pri;
u8 service_class;
- u8 daddr[ETH_ALEN];
- u8 saddr[ETH_ALEN];
+ struct {
+ u8 daddr[ETH_ALEN];
+ u8 saddr[ETH_ALEN];
+ } addr;
};

struct wl3501_md_confirm {
diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c
index 8ca5789c7b37..70307308635f 100644
--- a/drivers/net/wireless/wl3501_cs.c
+++ b/drivers/net/wireless/wl3501_cs.c
@@ -469,6 +469,7 @@ static int wl3501_send_pkt(struct wl3501_card *this, u8 *data, u16 len)
struct wl3501_md_req sig = {
.sig_id = WL3501_SIG_MD_REQ,
};
+ size_t sig_addr_len = sizeof(sig.addr);
u8 *pdata = (char *)data;
int rc = -EIO;

@@ -484,9 +485,9 @@ static int wl3501_send_pkt(struct wl3501_card *this, u8 *data, u16 len)
goto out;
}
rc = 0;
- memcpy(&sig.daddr[0], pdata, 12);
- pktlen = len - 12;
- pdata += 12;
+ memcpy(&sig.addr, pdata, sig_addr_len);
+ pktlen = len - sig_addr_len;
+ pdata += sig_addr_len;
sig.data = bf;
if (((*pdata) * 256 + (*(pdata + 1))) > 1500) {
u8 addr4[ETH_ALEN] = {
@@ -980,7 +981,8 @@ static inline void wl3501_md_ind_interrupt(struct net_device *dev,
} else {
skb->dev = dev;
skb_reserve(skb, 2); /* IP headers on 16 bytes boundaries */
- skb_copy_to_linear_data(skb, (unsigned char *)&sig.daddr, 12);
+ skb_copy_to_linear_data(skb, (unsigned char *)&sig.addr,
+ sizeof(sig.addr));
wl3501_receive(this, skb->data, pkt_len);
skb_put(skb, pkt_len);
skb->protocol = eth_type_trans(skb, dev);
--
2.30.2