2019-09-30 14:05:38

by Denis Efremov (Oracle)

Subject: [PATCH] ar5523: check NULL before memcpy() in ar5523_cmd()

memcpy() call with "idata == NULL && ilen == 0" results in undefined
behavior in ar5523_cmd(). For example, NULL is passed in callchain
"ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
adds idata check before memcpy() call in ar5523_cmd() to prevent an
undefined behavior.

Cc: Pontus Fuchs <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: [email protected]
Signed-off-by: Denis Efremov <[email protected]>
---
drivers/net/wireless/ath/ar5523/ar5523.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index b94759daeacc..f25af5bc5282 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -255,7 +255,8 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,

if (flags & AR5523_CMD_FLAG_MAGIC)
hdr->magic = cpu_to_be32(1 << 24);
- memcpy(hdr + 1, idata, ilen);
+ if (idata)
+ memcpy(hdr + 1, idata, ilen);

cmd->odata = odata;
cmd->olen = olen;
--
2.21.0

2019-09-30 15:39:24

by David Laight

Subject: RE: [PATCH] ar5523: check NULL before memcpy() in ar5523_cmd()

From: Denis Efremov
> Sent: 30 September 2019 15:02
>
> memcpy() call with "idata == NULL && ilen == 0" results in undefined
> behavior in ar5523_cmd(). For example, NULL is passed in callchain
> "ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
> adds idata check before memcpy() call in ar5523_cmd() to prevent an
> undefined behavior.
>
...
> Signed-off-by: Denis Efremov <[email protected]>
> ---
> drivers/net/wireless/ath/ar5523/ar5523.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
> index b94759daeacc..f25af5bc5282 100644
> --- a/drivers/net/wireless/ath/ar5523/ar5523.c
> +++ b/drivers/net/wireless/ath/ar5523/ar5523.c
> @@ -255,7 +255,8 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,
>
> if (flags & AR5523_CMD_FLAG_MAGIC)
> hdr->magic = cpu_to_be32(1 << 24);
> - memcpy(hdr + 1, idata, ilen);
> + if (idata)
> + memcpy(hdr + 1, idata, ilen);

That would be better as if (ilen) ...

David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

2019-09-30 20:41:45

by Denis Efremov (Oracle)

Subject: [PATCH v2] ar5523: check NULL before memcpy() in ar5523_cmd()

memcpy() call with "idata == NULL && ilen == 0" results in undefined
behavior in ar5523_cmd(). For example, NULL is passed in callchain
"ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
adds ilen check before memcpy() call in ar5523_cmd() to prevent an
undefined behavior.

Cc: Pontus Fuchs <[email protected]>
Cc: Kalle Valo <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: David Laight <[email protected]>
Cc: [email protected]
Signed-off-by: Denis Efremov <[email protected]>
---
V2: check ilen instead of idata as suggested by David Laight.

drivers/net/wireless/ath/ar5523/ar5523.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index b94759daeacc..da2d179430ca 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -255,7 +255,8 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,

if (flags & AR5523_CMD_FLAG_MAGIC)
hdr->magic = cpu_to_be32(1 << 24);
- memcpy(hdr + 1, idata, ilen);
+ if (ilen)
+ memcpy(hdr + 1, idata, ilen);

cmd->odata = odata;
cmd->olen = olen;
--
2.21.0

2019-10-02 17:22:55

by Kalle Valo

Subject: Re: [PATCH v2] ar5523: check NULL before memcpy() in ar5523_cmd()

Denis Efremov <[email protected]> wrote:

> memcpy() call with "idata == NULL && ilen == 0" results in undefined
> behavior in ar5523_cmd(). For example, NULL is passed in callchain
> "ar5523_stat_work() -> ar5523_cmd_write() -> ar5523_cmd()". This patch
> adds ilen check before memcpy() call in ar5523_cmd() to prevent an
> undefined behavior.
>
> Cc: Pontus Fuchs <[email protected]>
> Cc: Kalle Valo <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: David Laight <[email protected]>
> Cc: [email protected]
> Signed-off-by: Denis Efremov <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>

Patch applied to ath-next branch of ath.git, thanks.

315cee426f87 ar5523: check NULL before memcpy() in ar5523_cmd()

--
https://patchwork.kernel.org/patch/11167401/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches