FPII-2725:ALSA: info: Check for integer overflow in snd_info_entry_write() CVE-2017-0404 A-32510733
ALSA: info: Check for integer overflow in snd_info_entry_write()
snd_info_entry_write() resizes the buffer with an unsigned long
size argument that gets truncated because resize_info_buffer()
takes the size parameter as an unsigned int. On 64-bit kernels,
this causes the following copy_to_user() to write out-of-bounds
if (pos + count) can't be represented by an unsigned int.
Bug: 32510733
Change-Id: I9e8b55f93f2bd606b4a73b5a4525b71ee88c7c23
Signed-off-by: Siqi Lin <siqilin@google.com>
diff --git a/sound/core/info.c b/sound/core/info.c
index c1e611c..99198e1 100644
--- a/sound/core/info.c
+++ b/sound/core/info.c
@@ -260,6 +260,7 @@
struct snd_info_buffer *buf;
ssize_t size = 0;
loff_t pos;
+ unsigned long realloc_size;
data = file->private_data;
if (snd_BUG_ON(!data))
@@ -268,7 +269,8 @@
pos = *offset;
if (pos < 0 || (long) pos != pos || (ssize_t) count < 0)
return -EIO;
- if ((unsigned long) pos + (unsigned long) count < (unsigned long) pos)
+ realloc_size = (unsigned long) pos + (unsigned long) count;
+ if (realloc_size < (unsigned long) pos || realloc_size > UINT_MAX)
return -EIO;
switch (entry->content) {
case SNDRV_INFO_CONTENT_TEXT: