2021-03-31 22:45:12

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH v2 0/2][next] wl3501_cs: Fix out-of-bounds warnings

Fix the a couple of out-of-bounds warnings by making the code
a bit more structured.

This helps with the ongoing efforts to enable -Warray-bounds and
avoid confusing the compiler.

Link: https://github.com/KSPP/linux/issues/109

Changes in v2:
- Update changelog text in patch 1/2.
- Replace a couple of magic numbers with new variable sig_addr_len.

Gustavo A. R. Silva (2):
wl3501_cs: Fix out-of-bounds warning in wl3501_send_pkt
wl3501_cs: Fix out-of-bounds warning in wl3501_mgmt_join

drivers/net/wireless/wl3501.h | 28 ++++++++++++++++------------
drivers/net/wireless/wl3501_cs.c | 11 ++++++-----
2 files changed, 22 insertions(+), 17 deletions(-)

--
2.27.0


2021-03-31 22:45:42

by Gustavo A. R. Silva

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Subject: [PATCH v2 1/2][next] wl3501_cs: Fix out-of-bounds warning in wl3501_send_pkt

Fix the following out-of-bounds warning by enclosing
structure members daddr and saddr into new struct addr:

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 */
};

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],
because the address of the new struct object _addr_ is used as
destination, instead.

Also, this helps with the ongoing efforts to enable -Warray-bounds and
avoid confusing the compiler.

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <[email protected]>
Build-tested-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/60641d9b.2eNLedOGSdcSoAV2%[email protected]/
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Changes in v2:
- Update changelog text.
- Replace a couple of magic numbers with new variable sig_addr_len.

drivers/net/wireless/wl3501.h | 6 ++++--
drivers/net/wireless/wl3501_cs.c | 7 ++++---
2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h
index e98e04ee9a2c..ef9d605d8c88 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 {
diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c
index 8ca5789c7b37..e149ef81d6cc 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] = {
--
2.27.0

2021-03-31 22:47:04

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH v2 2/2][next] wl3501_cs: Fix out-of-bounds warning in wl3501_mgmt_join

Fix the following out-of-bounds warning by enclosing
some structure members into new struct req:

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]

Refactor the code, accordingly:

$ 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 {
u16 beacon_period; /* 36 2 */
u16 dtim_period; /* 38 2 */
u16 cap_info; /* 40 2 */
u8 bss_type; /* 42 1 */
u8 bssid[6]; /* 43 6 */
struct iw_mgmt_essid_pset ssid; /* 49 34 */
/* --- cacheline 1 boundary (64 bytes) was 19 bytes ago --- */
struct iw_mgmt_ds_pset ds_pset; /* 83 3 */
struct iw_mgmt_cf_pset cf_pset; /* 86 8 */
struct iw_mgmt_ibss_pset ibss_pset; /* 94 4 */
struct iw_mgmt_data_rset bss_basic_rset; /* 98 10 */
} req; /* 36 72 */

/* size: 108, cachelines: 2, members: 10 */
/* last cacheline: 44 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 _req_ enclosing all those adjacent
members is introduced, memcpy() doesn't overrun the length of
&sig.beacon_period, because the address of the new struct object
_req_ is used as the destination, instead.

Also, this helps with the ongoing efforts to enable -Warray-bounds and
avoid confusing the compiler.

Link: https://github.com/KSPP/linux/issues/109
Reported-by: kernel test robot <[email protected]>
Build-tested-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/lkml/60641d9b.2eNLedOGSdcSoAV2%[email protected]/
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
Changes in v2:
- None.

drivers/net/wireless/wl3501.h | 22 ++++++++++++----------
drivers/net/wireless/wl3501_cs.c | 4 ++--
2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h
index ef9d605d8c88..774d8cac046d 100644
--- a/drivers/net/wireless/wl3501.h
+++ b/drivers/net/wireless/wl3501.h
@@ -389,16 +389,18 @@ struct wl3501_join_req {
u16 probe_delay;
u8 timestamp[8];
u8 local_time[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 {
+ 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;
+ } req;
};

struct wl3501_join_confirm {
diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c
index e149ef81d6cc..399d3bd2ae76 100644
--- a/drivers/net/wireless/wl3501_cs.c
+++ b/drivers/net/wireless/wl3501_cs.c
@@ -590,7 +590,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas)
struct wl3501_join_req sig = {
.sig_id = WL3501_SIG_JOIN_REQ,
.timeout = 10,
- .ds_pset = {
+ .req.ds_pset = {
.el = {
.id = IW_MGMT_INFO_ELEMENT_DS_PARAMETER_SET,
.len = 1,
@@ -599,7 +599,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas)
},
};

- memcpy(&sig.beacon_period, &this->bss_set[stas].beacon_period, 72);
+ memcpy(&sig.req, &this->bss_set[stas].beacon_period, sizeof(sig.req));
return wl3501_esbq_exec(this, &sig, sizeof(sig));
}

--
2.27.0

2021-04-07 21:54:59

by Kees Cook

[permalink] [raw]
Subject: Re: [PATCH v2 2/2][next] wl3501_cs: Fix out-of-bounds warning in wl3501_mgmt_join

On Wed, Mar 31, 2021 at 04:45:34PM -0500, Gustavo A. R. Silva wrote:
> Fix the following out-of-bounds warning by enclosing
> some structure members into new struct req:
>
> 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]
>
> Refactor the code, accordingly:
>
> $ 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 {
> u16 beacon_period; /* 36 2 */
> u16 dtim_period; /* 38 2 */
> u16 cap_info; /* 40 2 */
> u8 bss_type; /* 42 1 */
> u8 bssid[6]; /* 43 6 */
> struct iw_mgmt_essid_pset ssid; /* 49 34 */
> /* --- cacheline 1 boundary (64 bytes) was 19 bytes ago --- */
> struct iw_mgmt_ds_pset ds_pset; /* 83 3 */
> struct iw_mgmt_cf_pset cf_pset; /* 86 8 */
> struct iw_mgmt_ibss_pset ibss_pset; /* 94 4 */
> struct iw_mgmt_data_rset bss_basic_rset; /* 98 10 */
> } req; /* 36 72 */

This section is the same as a large portion of struct wl3501_scan_confirm:

struct wl3501_scan_confirm {
u16 next_blk;
u8 sig_id;
u8 reserved;
u16 status;
char timestamp[8];
char localtime[8];

from here
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;
through here

u8 rssi;
};

It seems like maybe extracting that and using it in both structures
would make more sense?

>
> /* size: 108, cachelines: 2, members: 10 */
> /* last cacheline: 44 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 _req_ enclosing all those adjacent
> members is introduced, memcpy() doesn't overrun the length of
> &sig.beacon_period, because the address of the new struct object
> _req_ is used as the destination, instead.
>
> Also, this helps with the ongoing efforts to enable -Warray-bounds and
> avoid confusing the compiler.
>
> Link: https://github.com/KSPP/linux/issues/109
> Reported-by: kernel test robot <[email protected]>
> Build-tested-by: kernel test robot <[email protected]>
> Link: https://lore.kernel.org/lkml/60641d9b.2eNLedOGSdcSoAV2%[email protected]/
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> Changes in v2:
> - None.
>
> drivers/net/wireless/wl3501.h | 22 ++++++++++++----------
> drivers/net/wireless/wl3501_cs.c | 4 ++--
> 2 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/wireless/wl3501.h b/drivers/net/wireless/wl3501.h
> index ef9d605d8c88..774d8cac046d 100644
> --- a/drivers/net/wireless/wl3501.h
> +++ b/drivers/net/wireless/wl3501.h
> @@ -389,16 +389,18 @@ struct wl3501_join_req {
> u16 probe_delay;
> u8 timestamp[8];
> u8 local_time[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 {
> + 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;
> + } req;
> };
>
> struct wl3501_join_confirm {
> diff --git a/drivers/net/wireless/wl3501_cs.c b/drivers/net/wireless/wl3501_cs.c
> index e149ef81d6cc..399d3bd2ae76 100644
> --- a/drivers/net/wireless/wl3501_cs.c
> +++ b/drivers/net/wireless/wl3501_cs.c
> @@ -590,7 +590,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas)
> struct wl3501_join_req sig = {
> .sig_id = WL3501_SIG_JOIN_REQ,
> .timeout = 10,
> - .ds_pset = {
> + .req.ds_pset = {
> .el = {
> .id = IW_MGMT_INFO_ELEMENT_DS_PARAMETER_SET,
> .len = 1,
> @@ -599,7 +599,7 @@ static int wl3501_mgmt_join(struct wl3501_card *this, u16 stas)
> },
> };
>
> - memcpy(&sig.beacon_period, &this->bss_set[stas].beacon_period, 72);
> + memcpy(&sig.req, &this->bss_set[stas].beacon_period, sizeof(sig.req));

If not, then probably something like this should be added to make sure
nothing unexpected happens to change structure sizes:

BUILD_BUG_ON(sizeof(sig.req) != 72);

> return wl3501_esbq_exec(this, &sig, sizeof(sig));
> }
>
> --
> 2.27.0
>

--
Kees Cook