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

[Arjan van de Ven <arjan@infradead.org>]

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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