Hi Kees, On Thu, Nov 19, 2015 at 04:10:43PM -0800, Kees Cook wrote: > Normally, when a user can modify a file that has setuid or setgid bits, > those bits are cleared when they are not the file owner or a member of the > group. This is enforced when using write() directly but not when writing > to a shared mmap on the file. This could allow the file writer to gain > privileges by changing the binary without losing the setuid/setgid bits. > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > --- > mm/memory.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/memory.c b/mm/memory.c > index deb679c31f2a..4c970a4e0057 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2036,6 +2036,7 @@ static inline int wp_page_reuse(struct mm_struct *mm, > > if (!page_mkwrite) > file_update_time(vma->vm_file); > + file_remove_privs(vma->vm_file); I thought you said in one of the early mails of this thread that it didn't work. Or maybe I misunderstood. Also, don't you think we should move that into the if (!page_mkwrite) just like for the time update ? Willy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>