[lkml]   [2018]   [May]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] ALSA: control: fix a redundant-copy issue
On Sat, 05 May 2018 20:38:03 +0200,
Wenwen Wang wrote:
> In snd_ctl_elem_add_compat(), the fields of the struct 'data' need to be
> copied from the corresponding fields of the struct 'data32' in userspace.
> This is achieved by invoking copy_from_user() and get_user() functions. The
> problem here is that the 'type' field is copied twice. One is by
> copy_from_user() and one is by get_user(). Given that the 'type' field is
> not used between the two copies, the second copy is *completely* redundant
> and should be removed for better performance and cleanup. Also, these two
> copies can cause inconsistent data: as the struct 'data32' resides in
> userspace and a malicious userspace process can race to change the 'type'
> field between the two copies to cause inconsistent data. Depending on how
> the data is used in the future, such an inconsistency may cause potential
> security risks.
> For above reasons, we should take out the second copy.
> Signed-off-by: Wenwen Wang <>

Applied now, thanks.


 \ /
  Last update: 2018-05-13 10:27    [W:0.083 / U:1.492 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site