fs/xattr.c: zero out memory copied to userspace in getxattr
authorMichal Hocko <mhocko@suse.com>
Mon, 8 May 2017 22:57:24 +0000 (15:57 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 9 May 2017 00:15:12 +0000 (17:15 -0700)
commit81be3dee96346fbe08c31be5ef74f03f6b63cf68
tree0da1345c2f9b956b944c442e1df062dce6d692f9
parent847f716f9ec2c61f57690c871a307f1349d472d0
fs/xattr.c: zero out memory copied to userspace in getxattr

getxattr uses vmalloc to allocate memory if kzalloc fails.  This is
filled by vfs_getxattr and then copied to the userspace.  vmalloc,
however, doesn't zero out the memory so if the specific implementation
of the xattr handler is sloppy we can theoretically expose a kernel
memory.  There is no real sign this is really the case but let's make
sure this will not happen and use vzalloc instead.

Fixes: 779302e67835 ("fs/xattr.c:getxattr(): improve handling of allocation failures")
Link: http://lkml.kernel.org/r/20170306103327.2766-1-mhocko@kernel.org
Acked-by: Kees Cook <keescook@chromium.org>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org> [3.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/xattr.c