On 10/01/2015 06:38 PM, Linus Torvalds wrote: > On Thu, Oct 1, 2015 at 6:56 PM, Dave Hansen <dave@xxxxxxxx> wrote: >> >> Also, a quick ftrace showed that most mmap() callers that set PROT_EXEC >> also set PROT_READ. I'm just assuming that folks are setting PROT_READ >> but aren't _really_ going to read it, so we can safely deny them all >> access other than exec. > > That's a completely insane assumption. There are tons of reasons to > have code and read-only data in the same segment, and it's very > traditional. Just assuming that you only execute out of something that > has PROT_EXEC | PROT_READ is insane. Yes, it's insane, and I confirmed that ld.so actually reads some stuff out of the first page of the r-x part of the executable. But, it did find a bug in my code where I wouldn't allow instruction fetches to fault in pages in a pkey-protected area, so it wasn't a completely worthless exercise. -- 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>