Re: [PATCH] remoteproc: avoid stack overflow in debugfs file

[Ohad Ben-Cohen]

On Fri, Nov 20, 2015 at 7:26 PM, Arnd Bergmann  wrote:
> Recent gcc versions warn about reading from a negative offset of
> an on-stack array:
>
> drivers/remoteproc/remoteproc_debugfs.c: In function 'rproc_recovery_write':
> drivers/remoteproc/remoteproc_debugfs.c:167:9: warning: 'buf[4294967295u]' 
> may be used uninitialized in this function [-Wmaybe-uninitialized]
>
> I don't see anything in sys_write() that prevents us from
> being called with a zero 'count' argument, so we should
> add an extra check in rproc_recovery_write() to prevent the
> access and avoid the warning.
>
> Signed-off-by: Arnd Bergmann 
> Fixes: 2e37abb89a2e ("remoteproc: create a 'recovery' debugfs entry")

Applied to remoteproc-fixes, thanks.
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[PATCH] remoteproc: avoid stack overflow in debugfs file

[Arnd Bergmann]

Recent gcc versions warn about reading from a negative offset of
an on-stack array:

drivers/remoteproc/remoteproc_debugfs.c: In function 'rproc_recovery_write':
drivers/remoteproc/remoteproc_debugfs.c:167:9: warning: 'buf[4294967295u]' may 
be used uninitialized in this function [-Wmaybe-uninitialized]

I don't see anything in sys_write() that prevents us from
being called with a zero 'count' argument, so we should
add an extra check in rproc_recovery_write() to prevent the
access and avoid the warning.

Signed-off-by: Arnd Bergmann 
Fixes: 2e37abb89a2e ("remoteproc: create a 'recovery' debugfs entry")

diff --git a/drivers/remoteproc/remoteproc_debugfs.c 
b/drivers/remoteproc/remoteproc_debugfs.c
index 9d30809bb407..916af5096f57 100644
--- a/drivers/remoteproc/remoteproc_debugfs.c
+++ b/drivers/remoteproc/remoteproc_debugfs.c
@@ -156,7 +156,7 @@ rproc_recovery_write(struct file *filp, const char __user 
*user_buf,
char buf[10];
int ret;
 
-   if (count > sizeof(buf))
+   if (count < 1 || count > sizeof(buf))
return count;
 
ret = copy_from_user(buf, user_buf, count);

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