Fix overflow when converting ZST Vec to VecDeque #80003

Stupremee · 2020-12-13T09:07:57Z

let v = vec![(); 100];
let queue = VecDeque::from(v);
println!("{:?}", queue);

This code will currently panic with a capacity overflow.
This PR resolves this issue and makes the code run fine.

Resolves #78532

rust-highfive · 2020-12-13T09:08:00Z

r? @dtolnay

(rust-highfive has picked a reviewer for you, use r? to override)

library/alloc/src/collections/vec_deque/mod.rs

dtolnay

Thanks!

dtolnay · 2020-12-13T23:12:44Z

@bors r+

bors · 2020-12-13T23:12:46Z

📌 Commit 09d528e has been approved by dtolnay

…on-panic, r=dtolnay Fix overflow when converting ZST Vec to VecDeque ```rust let v = vec![(); 100]; let queue = VecDeque::from(v); println!("{:?}", queue); ``` This code will currently panic with a capacity overflow. This PR resolves this issue and makes the code run fine. Resolves rust-lang#78532

bors · 2020-12-14T12:35:14Z

⌛ Testing commit 09d528e with merge 3ea4f68cdcd9b95f5c31fb7730e5e44d66f9e59e...

bors · 2020-12-14T13:45:30Z

💔 Test failed - checks-actions

Stupremee · 2020-12-15T07:28:48Z

I don't know why the build failed but I think it has nothing to do with my PR?

dtolnay · 2020-12-15T11:23:28Z

The i686-msvc-1 job failed with:

error: linking with `link.exe` failed: exit code: 1201
  |
  = note: "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\Enterprise\\VC\\Tools\\MSVC\\14.28.29333\\bin\\HostX64\\x86\\link.exe" "/NOLOGO" "/NXCOMPAT" "/LARGEADDRESSAWARE" "/SAFESEH" "/LIBPATH:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.0.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.1.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.2.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.3.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.4.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.5.rcgu.o" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.main.7rcbfp3g-cgu.6.rcgu.o" "/OUT:D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.exe" "D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags\\main.4s37gsrti678ik8u.rcgu.o" "/OPT:REF,NOICF" "/DEBUG" "/NATVIS:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\etc\\intrinsic.natvis" "/NATVIS:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\etc\\liballoc.natvis" "/NATVIS:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\etc\\libcore.natvis" "/NATVIS:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\etc\\libstd.natvis" "/LIBPATH:D:/a/rust/rust/build/i686-pc-windows-msvc/test/run-make-fulldeps/override-aliased-flags/override-aliased-flags" "/LIBPATH:D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libstd-2deb73d3b5fa87cf.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libpanic_unwind-15c6a7fdf91ef35a.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\librustc_demangle-e074a35b22c4b5d2.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libhashbrown-6c3c9ebd17ae006e.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\librustc_std_workspace_alloc-13e844b011774ae1.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libunwind-a91a7398553297ff.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libcfg_if-35a0f6d337703982.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\liblibc-fe3cebfa1c67a4da.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\liballoc-db1c1d00bd877cb8.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\librustc_std_workspace_core-99335de001fe3f12.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libcore-c8fa98e615898128.rlib" "D:\\a\\rust\\rust\\build\\i686-pc-windows-msvc\\stage2\\lib\\rustlib\\i686-pc-windows-msvc\\lib\\libcompiler_builtins-38e39f9411889523.rlib" "advapi32.lib" "ws2_32.lib" "userenv.lib" "msvcrt.lib"
  = note: LINK : fatal error LNK1201: error writing to program database 'D:\a\rust\rust\build\i686-pc-windows-msvc\test\run-make-fulldeps\override-aliased-flags\override-aliased-flags\main.pdb'; check for insufficient disk space, invalid path, or insufficient privilege

@bors retry

…on-panic, r=dtolnay Fix overflow when converting ZST Vec to VecDeque ```rust let v = vec![(); 100]; let queue = VecDeque::from(v); println!("{:?}", queue); ``` This code will currently panic with a capacity overflow. This PR resolves this issue and makes the code run fine. Resolves rust-lang#78532

tmiasko · 2020-12-17T12:15:03Z

library/alloc/src/collections/vec_deque/mod.rs

+            // because `usize::MAX` (the capacity returned by `capacity()` for ZST)
+            // is not a power of two and thus it'll always try
+            // to reserve more memory which will panic for ZST (rust-lang/rust#78532)
+            if (!buf.capacity().is_power_of_two() && mem::size_of::<T>() != 0)


Maximum len of ZST Vec is larger than maximum len of ZST VecDeque (MAXIMUM_ZST_CAPACITY - 1), which would be another thing to check before constructing VecDeque.

I'm not sure if this should be changed in this PR, but it's definitely a check that should be added I think.

Fair. I mentioned it here, because it wasn't an issue so far, but will be as a result of changes in this PR.

You can just open a new issue👍

We now create a VecDeque with a capacity which is not a power of two here, breaking one of its invariants.

This is either unsound or that invariant isn't actually required anywhere and we should remove it.

Rollup of 5 pull requests Successful merges: - rust-lang#78164 (Prefer regions with an `external_name` in `approx_universal_upper_bound`) - rust-lang#80003 (Fix overflow when converting ZST Vec to VecDeque) - rust-lang#80023 (Enhance error message when misspelled label to value in break expression) - rust-lang#80046 (Add more documentation to `Diagnostic` and `DiagnosticBuilder`) - rust-lang#80109 (Remove redundant and unreliable coverage test results) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

fix panic if converting ZST Vec to VecDeque

0f30b7d

rust-highfive assigned dtolnay Dec 13, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Dec 13, 2020

Stupremee added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. A-collections Area: std::collections. A-zst Area: Zero-sized types (ZST). labels Dec 13, 2020

replace assert! with assert_eq!

d75618e

the8472 reviewed Dec 13, 2020

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library/alloc/src/collections/vec_deque/mod.rs Outdated Show resolved Hide resolved

fix typo

09d528e

dtolnay approved these changes Dec 13, 2020

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 13, 2020

Dylan-DPC-zz mentioned this pull request Dec 14, 2020

Rollup of 7 pull requests #80018

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bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Dec 14, 2020

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 15, 2020

Dylan-DPC-zz mentioned this pull request Dec 15, 2020

Rollup of 10 pull requests #80061

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Dylan-DPC-zz mentioned this pull request Dec 15, 2020

Rollup of 10 pull requests #80063

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Dylan-DPC-zz mentioned this pull request Dec 15, 2020

Rollup of 11 pull requests #80064

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Dylan-DPC-zz mentioned this pull request Dec 16, 2020

Rollup of 10 pull requests #80078

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Dylan-DPC-zz mentioned this pull request Dec 16, 2020

Rollup of 10 pull requests #80084

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Dylan-DPC-zz mentioned this pull request Dec 16, 2020

Rollup of 11 pull requests #80093

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tmiasko reviewed Dec 17, 2020

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Dylan-DPC-zz mentioned this pull request Dec 17, 2020

Rollup of 5 pull requests #80138

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bors merged commit 2e9ed6f into rust-lang:master Dec 18, 2020

rustbot added this to the 1.50.0 milestone Dec 18, 2020

tmiasko mentioned this pull request Dec 18, 2020

VecDeque from Vec with ZST elements breaks internal invariants #80167

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ehuss mentioned this pull request Feb 8, 2021

spurious CI error for MSVC #81890

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Fix overflow when converting ZST Vec to VecDeque #80003

Fix overflow when converting ZST Vec to VecDeque #80003

Stupremee commented Dec 13, 2020

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Stupremee commented Dec 15, 2020

dtolnay commented Dec 15, 2020

tmiasko Dec 17, 2020

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lcnr Dec 18, 2020

Fix overflow when converting ZST Vec to VecDeque #80003

Fix overflow when converting ZST Vec to VecDeque #80003

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