From: Michal Hocko <mhocko@xxxxxxxx>
Subject: 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@xxxxxxxxxx
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reported-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.6+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/xattr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/xattr.c~xattr-zero-out-memory-copied-to-userspace-in-getxattr fs/xattr.c
--- a/fs/xattr.c~xattr-zero-out-memory-copied-to-userspace-in-getxattr
+++ a/fs/xattr.c
@@ -530,7 +530,7 @@ getxattr(struct dentry *d, const char __
size = XATTR_SIZE_MAX;
kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
if (!kvalue) {
- kvalue = vmalloc(size);
+ kvalue = vzalloc(size);
if (!kvalue)
return -ENOMEM;
}
_