| Message ID | 20150820103037.GA5521@mwanda (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
Hi Dan, > From: Dan Carpenter [mailto:dan.carpenter@oracle.com] > Sent: Thursday, August 20, 2015 4:01 PM > To: Amitkumar Karwar; Bing Zhao > Cc: Nishant Sarmukadam; Kalle Valo; linux-wireless@vger.kernel.org; > kernel-janitors@vger.kernel.org > 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 <dan.carpenter@oracle.com> > > 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 <akarwar@marvell.com> Regards, Amitkumar -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Dan Carpenter <dan.carpenter@oracle.com> 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 <dan.carpenter@oracle.com> 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?
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; }
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 <dan.carpenter@oracle.com> -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html