From 3e17d191fa47b9ab262d0efa3a39e500e9fb1667 Mon Sep 17 00:00:00 2001 From: Sebastian Hahn Date: Mon, 17 Feb 2020 18:55:41 +0100 Subject: Revert "Remove `checked_add` in `Layout::repeat`" This fixes a a segfault in safe code, a stable regression. Reported in \#69225. This reverts commit a983e0590a43ed8b0f60417828efd4e79b51f494. Also adds a test for the expected behaviour. --- src/libcore/alloc.rs | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'src/libcore') diff --git a/src/libcore/alloc.rs b/src/libcore/alloc.rs index 71f7f971eab..a04e75bc7ce 100644 --- a/src/libcore/alloc.rs +++ b/src/libcore/alloc.rs @@ -241,11 +241,13 @@ impl Layout { #[unstable(feature = "alloc_layout_extra", issue = "55724")] #[inline] pub fn repeat(&self, n: usize) -> Result<(Self, usize), LayoutErr> { - // This cannot overflow. Quoting from the invariant of Layout: - // > `size`, when rounded up to the nearest multiple of `align`, - // > must not overflow (i.e., the rounded value must be less than - // > `usize::MAX`) - let padded_size = self.size() + self.padding_needed_for(self.align()); + // Warning, removing the checked_add here led to segfaults in #67174. Further + // analysis in #69225 seems to indicate that this is an LTO-related + // miscompilation, so #67174 might be able to be reapplied in the future. + let padded_size = self + .size() + .checked_add(self.padding_needed_for(self.align())) + .ok_or(LayoutErr { private: () })?; let alloc_size = padded_size.checked_mul(n).ok_or(LayoutErr { private: () })?; unsafe { -- cgit 1.4.1-3-g733a5