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Subject[PATCH 1/9] Fix bound checks for copy_from_user in the acpi /proc code

From: Arjan van de Ven <arjan@linux.intel.com>
Subject: [PATCH 1/9] Fix bound checks for copy_from_user in the acpi /proc code
CC: Len Brown <lenb@kernel.org>

The ACPI /proc write() code takes an unsigned length argument like any write()
function, but then assigned it to a *signed* integer called "len".
Only after this is a sanity check for len done to make it not larger than 4.

Due to the type change a len < 0 is in principle also possible; this patch
adds a check for this.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>

diff --git a/drivers/acpi/proc.c b/drivers/acpi/proc.c
index d0d550d..f8b6f55 100644
--- a/drivers/acpi/proc.c
+++ b/drivers/acpi/proc.c
@@ -398,6 +398,8 @@ acpi_system_write_wakeup_device(struct file *file,

if (len > 4)
len = 4;
+ if (len < 0)
+ return -EFAULT;

if (copy_from_user(strbuf, buffer, len))
return -EFAULT;

--
Arjan van de Ven Intel Open Source Technology Centre
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