| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 52/80] fs/xattr.c: zero out memory copied to userspace in getxattr | Date | Thu, 18 May 2017 12:48:34 +0200 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Michal Hocko <mhocko@suse.com>
commit 81be3dee96346fbe08c31be5ef74f03f6b63cf68 upstream.
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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/xattr.c +++ b/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; }
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