There were several bugs here.
1) The done label was in the wrong place so we didn't copy any
information out when there was no command given.
2) We were using PAGE_SIZE as the size of the buffer instead of
"PAGE_SIZE - pos".
3) snprintf() returns the number of characters that would have been
printed if there were enough space. If there was not enough space
(and we had fixed the memory corruption bug #2) then it would result
in an information leak when we do simple_read_from_buffer(). I've
changed it to use scnprintf() instead.
I also removed the initialization at the start of the function, because
I thought it made the code a little more clear.
Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell mwifiex driver')
Signed-off-by: Dan Carpenter <[email protected]>
diff --git a/drivers/net/wireless/mwifiex/debugfs.c b/drivers/net/wireless/mwifiex/debugfs.c
index 5a0636d4..bd2f5d2 100644
--- a/drivers/net/wireless/mwifiex/debugfs.c
+++ b/drivers/net/wireless/mwifiex/debugfs.c
@@ -731,7 +731,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
(struct mwifiex_private *) file->private_data;
unsigned long addr = get_zeroed_page(GFP_KERNEL);
char *buf = (char *) addr;
- int pos = 0, ret = 0, i;
+ int pos, ret, i;
u8 value[MAX_EEPROM_DATA];
if (!buf)
@@ -739,7 +739,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
if (saved_offset == -1) {
/* No command has been given */
- pos += snprintf(buf, PAGE_SIZE, "0");
+ pos = snprintf(buf, PAGE_SIZE, "0");
goto done;
}
@@ -751,14 +751,14 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
goto done;
}
- pos += snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);
+ pos = snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);
for (i = 0; i < saved_bytes; i++)
- pos += snprintf(buf + strlen(buf), PAGE_SIZE, "%d ", value[i]);
+ pos += scnprintf(buf + pos, PAGE_SIZE - pos, "%d ", value[i]);
+done:
ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
-done:
free_page(addr);
return ret;
}
Hi Dan,
> From: Dan Carpenter [mailto:[email protected]]
> Sent: Thursday, August 20, 2015 4:01 PM
> To: Amitkumar Karwar; Bing Zhao
> Cc: Nishant Sarmukadam; Kalle Valo; [email protected];
> [email protected]
> Subject: [patch] mwifiex: fix mwifiex_rdeeprom_read()
>
> There were several bugs here.
>
> 1) The done label was in the wrong place so we didn't copy any
> information out when there was no command given.
>
> 2) We were using PAGE_SIZE as the size of the buffer instead of
> "PAGE_SIZE - pos".
>
> 3) snprintf() returns the number of characters that would have been
> printed if there were enough space. If there was not enough space
> (and we had fixed the memory corruption bug #2) then it would result
> in an information leak when we do simple_read_from_buffer(). I've
> changed it to use scnprintf() instead.
>
> I also removed the initialization at the start of the function, because
> I thought it made the code a little more clear.
>
> Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell
> mwifiex driver')
> Signed-off-by: Dan Carpenter <[email protected]>
>
> diff --git a/drivers/net/wireless/mwifiex/debugfs.c
> b/drivers/net/wireless/mwifiex/debugfs.c
> index 5a0636d4..bd2f5d2 100644
> --- a/drivers/net/wireless/mwifiex/debugfs.c
> +++ b/drivers/net/wireless/mwifiex/debugfs.c
> @@ -731,7 +731,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user
> *ubuf,
> (struct mwifiex_private *) file->private_data;
> unsigned long addr = get_zeroed_page(GFP_KERNEL);
> char *buf = (char *) addr;
> - int pos = 0, ret = 0, i;
> + int pos, ret, i;
> u8 value[MAX_EEPROM_DATA];
>
> if (!buf)
> @@ -739,7 +739,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user
> *ubuf,
>
> if (saved_offset == -1) {
> /* No command has been given */
> - pos += snprintf(buf, PAGE_SIZE, "0");
> + pos = snprintf(buf, PAGE_SIZE, "0");
> goto done;
> }
>
> @@ -751,14 +751,14 @@ mwifiex_rdeeprom_read(struct file *file, char
> __user *ubuf,
> goto done;
> }
>
> - pos += snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset,
> saved_bytes);
> + pos = snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset,
> saved_bytes);
>
> for (i = 0; i < saved_bytes; i++)
> - pos += snprintf(buf + strlen(buf), PAGE_SIZE, "%d ",
> value[i]);
> + pos += scnprintf(buf + pos, PAGE_SIZE - pos, "%d ",
> value[i]);
>
> +done:
> ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
>
> -done:
> free_page(addr);
> return ret;
> }
Looks good.
Acked-by: Amitkumar Karwar <[email protected]>
Regards,
Amitkumar
Dan Carpenter <[email protected]> writes:
> There were several bugs here.
>
> 1) The done label was in the wrong place so we didn't copy any
> information out when there was no command given.
>
> 2) We were using PAGE_SIZE as the size of the buffer instead of
> "PAGE_SIZE - pos".
>
> 3) snprintf() returns the number of characters that would have been
> printed if there were enough space. If there was not enough space
> (and we had fixed the memory corruption bug #2) then it would result
> in an information leak when we do simple_read_from_buffer(). I've
> changed it to use scnprintf() instead.
>
> I also removed the initialization at the start of the function, because
> I thought it made the code a little more clear.
>
> Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell mwifiex driver')
> Signed-off-by: Dan Carpenter <[email protected]>
I see a new warning:
drivers/net/wireless/mwifiex/debugfs.c:760:31: warning: pos may be used uninitialized in this function [-Wuninitialized]
Is it a valid warning or should I apply the patch anyway?
--
Kalle Valo
> There were several bugs here.
>
> 1) The done label was in the wrong place so we didn't copy any
> information out when there was no command given.
>
> 2) We were using PAGE_SIZE as the size of the buffer instead of
> "PAGE_SIZE - pos".
>
> 3) snprintf() returns the number of characters that would have been
> printed if there were enough space. If there was not enough space
> (and we had fixed the memory corruption bug #2) then it would result
> in an information leak when we do simple_read_from_buffer(). I've
> changed it to use scnprintf() instead.
>
> I also removed the initialization at the start of the function, because
> I thought it made the code a little more clear.
>
> Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell mwifiex driver')
> Signed-off-by: Dan Carpenter <[email protected]>
> Acked-by: Amitkumar Karwar <[email protected]>
Thanks, applied to wireless-drivers-next.git.
Kalle Valo
There were several bugs here.
1) The done label was in the wrong place so we didn't copy any
information out when there was no command given.
2) We were using PAGE_SIZE as the size of the buffer instead of
"PAGE_SIZE - pos".
3) snprintf() returns the number of characters that would have been
printed if there were enough space. If there was not enough space
(and we had fixed the memory corruption bug #2) then it would result
in an information leak when we do simple_read_from_buffer(). I've
changed it to use scnprintf() instead.
I also removed the initialization at the start of the function, because
I thought it made the code a little more clear.
Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell mwifiex driver')
Signed-off-by: Dan Carpenter <[email protected]>
---
v2: My first part introduced a bug. :(
Sorry for the delay on this.
diff --git a/drivers/net/wireless/mwifiex/debugfs.c b/drivers/net/wireless/mwifiex/debugfs.c
index 5a0636d4..5583856 100644
--- a/drivers/net/wireless/mwifiex/debugfs.c
+++ b/drivers/net/wireless/mwifiex/debugfs.c
@@ -731,7 +731,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
(struct mwifiex_private *) file->private_data;
unsigned long addr = get_zeroed_page(GFP_KERNEL);
char *buf = (char *) addr;
- int pos = 0, ret = 0, i;
+ int pos, ret, i;
u8 value[MAX_EEPROM_DATA];
if (!buf)
@@ -739,7 +739,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
if (saved_offset == -1) {
/* No command has been given */
- pos += snprintf(buf, PAGE_SIZE, "0");
+ pos = snprintf(buf, PAGE_SIZE, "0");
goto done;
}
@@ -748,17 +748,17 @@ mwifiex_rdeeprom_read(struct file *file, char __user *ubuf,
(u16) saved_bytes, value);
if (ret) {
ret = -EINVAL;
- goto done;
+ goto out_free;
}
- pos += snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);
+ pos = snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset, saved_bytes);
for (i = 0; i < saved_bytes; i++)
- pos += snprintf(buf + strlen(buf), PAGE_SIZE, "%d ", value[i]);
-
- ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
+ pos += scnprintf(buf + pos, PAGE_SIZE - pos, "%d ", value[i]);
done:
+ ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
+out_free:
free_page(addr);
return ret;
}
Hi Dan,
> From: Dan Carpenter [mailto:[email protected]]
> Sent: Monday, September 21, 2015 9:50 PM
> To: Amitkumar Karwar
> Cc: Nishant Sarmukadam; Kalle Valo; [email protected];
> [email protected]
> Subject: [patch v2] mwifiex: fix mwifiex_rdeeprom_read()
>
> There were several bugs here.
>
> 1) The done label was in the wrong place so we didn't copy any
> information out when there was no command given.
>
> 2) We were using PAGE_SIZE as the size of the buffer instead of
> "PAGE_SIZE - pos".
>
> 3) snprintf() returns the number of characters that would have been
> printed if there were enough space. If there was not enough space
> (and we had fixed the memory corruption bug #2) then it would result
> in an information leak when we do simple_read_from_buffer(). I've
> changed it to use scnprintf() instead.
>
> I also removed the initialization at the start of the function, because
> I thought it made the code a little more clear.
>
> Fixes: 5e6e3a92b9a4 ('wireless: mwifiex: initial commit for Marvell
> mwifiex driver')
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> v2: My first part introduced a bug. :(
>
> Sorry for the delay on this.
>
> diff --git a/drivers/net/wireless/mwifiex/debugfs.c
> b/drivers/net/wireless/mwifiex/debugfs.c
> index 5a0636d4..5583856 100644
> --- a/drivers/net/wireless/mwifiex/debugfs.c
> +++ b/drivers/net/wireless/mwifiex/debugfs.c
> @@ -731,7 +731,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user
> *ubuf,
> (struct mwifiex_private *) file->private_data;
> unsigned long addr = get_zeroed_page(GFP_KERNEL);
> char *buf = (char *) addr;
> - int pos = 0, ret = 0, i;
> + int pos, ret, i;
> u8 value[MAX_EEPROM_DATA];
>
> if (!buf)
> @@ -739,7 +739,7 @@ mwifiex_rdeeprom_read(struct file *file, char __user
> *ubuf,
>
> if (saved_offset == -1) {
> /* No command has been given */
> - pos += snprintf(buf, PAGE_SIZE, "0");
> + pos = snprintf(buf, PAGE_SIZE, "0");
> goto done;
> }
>
> @@ -748,17 +748,17 @@ mwifiex_rdeeprom_read(struct file *file, char
> __user *ubuf,
> (u16) saved_bytes, value);
> if (ret) {
> ret = -EINVAL;
> - goto done;
> + goto out_free;
> }
>
> - pos += snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset,
> saved_bytes);
> + pos = snprintf(buf, PAGE_SIZE, "%d %d ", saved_offset,
> saved_bytes);
>
> for (i = 0; i < saved_bytes; i++)
> - pos += snprintf(buf + strlen(buf), PAGE_SIZE, "%d ",
> value[i]);
> -
> - ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
> + pos += scnprintf(buf + pos, PAGE_SIZE - pos, "%d ",
> value[i]);
>
> done:
> + ret = simple_read_from_buffer(ubuf, count, ppos, buf, pos);
> +out_free:
> free_page(addr);
> return ret;
> }
Acked-by: Amitkumar Karwar <[email protected]>
Regards,
Amitkumar