[PATCH] wireless: ath6kl: fix out of bound from length.

[PATCH] wireless: ath6kl: fix out of bound from length.

[xiaolinkui]

From: Linkui Xiao <xiaolinkui@kylinos.cn>

If length from debug_buf.length is 4294967293 (0xfffffffd), the result of
ALIGN(size, 4) will be 0.

	length = ALIGN(length, 4);

In case of length == 4294967293 after four-byte aligned access, length will
become 0.

	ret = ath6kl_diag_read(ar, address, buf, length);

will fail to read.

Fixes: bc07ddb29a7b ("ath6kl: read fwlog from firmware ring buffer")
Signed-off-by: Linkui Xiao <xiaolinkui@kylinos.cn>
---
 drivers/net/wireless/ath/ath6kl/core.h | 2 +-
 drivers/net/wireless/ath/ath6kl/main.c | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/ath/ath6kl/core.h b/drivers/net/wireless/ath/ath6kl/core.h
index 77e052336eb5..b90ad9541e09 100644
--- a/drivers/net/wireless/ath/ath6kl/core.h
+++ b/drivers/net/wireless/ath/ath6kl/core.h
@@ -907,7 +907,7 @@ void ath6kl_cleanup_amsdu_rxbufs(struct ath6kl *ar);
 int ath6kl_diag_write32(struct ath6kl *ar, u32 address, __le32 value);
 int ath6kl_diag_write(struct ath6kl *ar, u32 address, void *data, u32 length);
 int ath6kl_diag_read32(struct ath6kl *ar, u32 address, u32 *value);
-int ath6kl_diag_read(struct ath6kl *ar, u32 address, void *data, u32 length);
+int ath6kl_diag_read(struct ath6kl *ar, u32 address, void *data, size_t length);
 int ath6kl_read_fwlogs(struct ath6kl *ar);
 void ath6kl_init_profile_info(struct ath6kl_vif *vif);
 void ath6kl_tx_data_cleanup(struct ath6kl *ar);
diff --git a/drivers/net/wireless/ath/ath6kl/main.c b/drivers/net/wireless/ath/ath6kl/main.c
index d3aa9e7a37c2..e9e66d5ad505 100644
--- a/drivers/net/wireless/ath/ath6kl/main.c
+++ b/drivers/net/wireless/ath/ath6kl/main.c
@@ -233,7 +233,7 @@ int ath6kl_diag_write32(struct ath6kl *ar, u32 address, __le32 value)
 	return 0;
 }
 
-int ath6kl_diag_read(struct ath6kl *ar, u32 address, void *data, u32 length)
+int ath6kl_diag_read(struct ath6kl *ar, u32 address, void *data, size_t length)
 {
 	u32 count, *buf = data;
 	int ret;
@@ -272,7 +272,8 @@ int ath6kl_read_fwlogs(struct ath6kl *ar)
 {
 	struct ath6kl_dbglog_hdr debug_hdr;
 	struct ath6kl_dbglog_buf debug_buf;
-	u32 address, length, firstbuf, debug_hdr_addr;
+	u32 address, firstbuf, debug_hdr_addr;
+	size_t length;
 	int ret, loop;
 	u8 *buf;
 
-- 
2.17.1

Re: [PATCH] wireless: ath6kl: fix out of bound from length.

[Dan Carpenter]

On Thu, Jul 21, 2022 at 11:21:58AM +0800, xiaolinkui wrote:
> From: Linkui Xiao <xiaolinkui@kylinos.cn>
> 
> If length from debug_buf.length is 4294967293 (0xfffffffd), the result of
> ALIGN(size, 4) will be 0.
> 
> 	length = ALIGN(length, 4);
> 
> In case of length == 4294967293 after four-byte aligned access, length will
> become 0.
> 
> 	ret = ath6kl_diag_read(ar, address, buf, length);
> 
> will fail to read.

It looks like "length" is untrustworthy.  Generally, I kind of distrust
all endian data by default, but I dug a bit deeper and I don't trust it.

Unfortunately, if "length" is larger than ATH6KL_FWLOG_PAYLOAD_SIZE
(1500) then we are screwed.  Can you add a check for that instead?
Please check my work on this because I didn't look *super* carefully.

No need to make any changes to the types, just add the upper bounds
check on ATH6KL_FWLOG_PAYLOAD_SIZE.  The type changes didn't fix the bug
on 32 bit systems anyway...

regards,
dan carpenter