On Wed, Jan 26, 2022 at 08:08:14PM +0000, Matthew Wilcox wrote: > On Wed, Jan 26, 2022 at 11:58:39AM -0800, Kees Cook wrote: > > We can't mutate argc; it'll turn at least some userspace into an > > infinite loop: > > https://sources.debian.org/src/valgrind/1:3.18.1-1/none/tests/execve.c/?hl=22#L22 > > How does that become an infinite loop? We obviously wouldn't mutate > argc in the caller, just the callee. Oh, sorry, I misread. It's using /bin/true, not argv[0] (another bit of code I found was using argv[0]). Yeah, {"", NULL} could work. > Also, there's a version of this where we only mutate argc if we're > executing a setuid program, which would remove the privilege > escalation part of things. True; though I'd like to keep the logic as non-specialized as possible. I don't like making stuff conditional on privilege boundaries if we can make it always happen. -- Kees Cook
