From 220605a5fd03d7181d55b59d6bd147c86a4c8bc0 Mon Sep 17 00:00:00 2001 From: Chirantan Ekbote Date: Thu, 14 Nov 2019 18:36:06 +0900 Subject: io_jail: Replace rlim_t with rlim64_t rlim_t is defined as an unsigned long but importantly, it is defined as what the _kernel_ thinks is an unsigned long. This means that when you have a 32-bit userspace and a 64-bit kernel (like we do for arm64 chromebooks), rlim_t is 64 bits. This isn't really a problem for C and C++ code because they use the headers from the kernel where rlim_t is properly sized but it doesn't really work for rust. The libc crate defines rlim_t as an alias for ::std::os::raw::c_ulong, which leads to the rust compiler thinking that it has a 32 bit width. Hilarity ensues when you attempt to cross the rust -> C FFI barrier with these conflicting definitions. The rust compiler thinks the parameters can fit in 32 bit registers so it puts the `cur` parameter in r2 and the `max` parameter in r3. On the other hand, the C code knows that the parameters are 64-bit values and combines r2/r3 to create the 64-bit `cur` value and uses the first 8 bytes on the stack as the `max` value. This leads to a `cur` value that is way too large and a nonsensical `max` value that depends on whatever happened to be on the stack at the time. Fix this by changing the library bindings to u64 and the Minijail::set_rlimit parameters to rlim64_t. Once we add a method to minijail that accepts rlim64_t's we can switch the library bindings to use that as well. BUG=b:136128319 TEST=`tast run vm.Virtiofs` on kevin Change-Id: I8f58923c4768ecfe827d2a5d73c72dc778fe419c Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1916560 Reviewed-by: Chirantan Ekbote Tested-by: Chirantan Ekbote Tested-by: kokoro Commit-Queue: Chirantan Ekbote --- src/linux.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src') diff --git a/src/linux.rs b/src/linux.rs index bd6ee5c..ffdb829 100644 --- a/src/linux.rs +++ b/src/linux.rs @@ -287,7 +287,7 @@ impl AsRawFd for TaggedControlSocket { } } -fn get_max_open_files() -> Result { +fn get_max_open_files() -> Result { let mut buf = String::with_capacity(32); File::open("/proc/sys/fs/file-max") .and_then(|mut f| f.read_to_string(&mut buf)) -- cgit 1.4.1