From 4faa6d2e9b53546823882d8889820ff9ce3c372f Mon Sep 17 00:00:00 2001 From: Siqi Lin Date: Wed, 2 Nov 2016 16:51:08 -0700 Subject: [PATCH] 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 --- sound/core/info.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/sound/core/info.c b/sound/core/info.c index 418b4ec43cadb..a4af0ba92d30f 100644 --- a/sound/core/info.c +++ b/sound/core/info.c @@ -253,6 +253,7 @@ static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer 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)) @@ -261,7 +262,8 @@ static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer 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: